Since reading comments from you beautiful people, we want clarify a couple things. First, the fact that ethernet is digital (as opposed to analog) is not the reason that these splitters don't work. In fact, some digital signals can be split, such as I2C, DTV, or ARINC. Second, many other commenters are suggesting using these splitters as passive hubs, but while in the past that could have been a possibility, these splitters aren't wired correctly for that . The transmission pins on the sending device need to connect to the receiving pins on the other end. Simply wiring pin 1 to pin 1, 2 to 2, etc. as we see here does not work. While some of those old/deprecated features of the earlier ethernet standards could have enabled devices similar to these to work with very old network adapters, few, if any modern network adapters support these features and, ultimately, the wiring diagrams presented on the product page for these don't suggest that the seller intends customers to use them in that way. Our apologies for not making all this obvious in the video! Now here's some link to real solutions: Buy a TP-Link 5 Port Gigabit Ethernet Switch: lmg.gg/lp5ev Buy a TP-Link 5 Port Ethernet Switch: lmg.gg/3F5f5 Purchases made through some store links may provide some compensation to Linus Media Group.

It's honestly impressive these companies realized less technically inclined people would search for "ethernet splitter" instead of an actual switch, then made a product that looked exactly like what said people were expecting, albeit somehow worse and more expensive than a 2-port ethernet switch. If only they had used their powers for good...

Hi Linus, random network engineer speaking. That splitter might work if you change all of your network interfaces to half duplex. Half duplex would need to be set on both of the computers connected to the splitter as well as the switch port the splitter plugs into. Half duplex uses a protocol called Cable Sense Multiple Access with Collision Detection (or CSMA/CD for short). Its a protocol that harkens back to the days of yore when network devices communicated over a single wire (like token rings and hubs). On a Windows PC you should be able to change the duplex settings from the network device properties in device manager. As for the switch, you will need a managed switch that allows you to change the port settings.

I made this back in college. Had 2 machines and I was lazy and didn't want to run multiple cables and we didn't have access to a bunch of consumer grade switches. There was already a jack at my station so I made my own 'splitter' with 6 Rj45 connectors (3 at each end). My networking instructor was both disappointed and impressed when he saw it. He knew I knew it was wrong. But also, he appreciated the ingenuity of it.

I used to make my own splitters in the military when running another cable wasn't possible or feasible. Was back in the Cat5e days, so we only had 100Mbps switch ports at the edge anyway. Thanks for bringing back some good memories! 😂

Time to daisy chain splitters into a Christmas tree of sadness.

I did this once a couple decades ago. The building facility manager would not cooperate between our two suites, so I used the telephone panel to split each pair to their own phone jack in the closet and connected the switches via a custom cable feeding all 4 pairs back into an ethernet keystone on each end. Performance was good enough to allow us to complete the move from one suite to the other over a week instead of having to do it overnight. Once done, I removed my handiwork from the closet and kept the two dongles as a trophy for my ingenuity. :)

We used to split CAT-5 cable into two cable connections when I was in the Air Force all the time. My unit's mission was to setup deployable PC/telephone equipment in the field and the less cable we had to run the better. We would even drop a ethernet link to a PC and then use the extra wire pairs for telephones.

Fun video. What you built here was a Data / Data RJ45 Economiser, you can also buy them in Data / Voice and Voice / Voice. They often have different colour strain relief boots to indicate by glance what they are. Basically on the Voice versions they are wired up using the middle 2 pins (Pin 4 and 5 blue pair) and the brown pair (Pin 7 and 8). They have been around for many years, but not many know about them 👍 The Data / Voice version is sometimes useful for pushing good old fashioned dial tone down the 1 Ethernet cable with 100Mbps internet as well.

Working at Radioshack I heard this a thousand times. We had an adapter that was exactly like the adapter featured in the video. They would refuse to buy the slightly more expensive ethernet switch regardless of how much I protested. Some of them came back and usually apologized; others I'm sure went to other stores to avoid seeing my face again lmao

Surprisingly, this video has helped me diagnose a network issue at home today. I noticed that a wired connection between 2 rooms is running at 100Mbps, which led me to think that one internal wire is broken/disconnected. I never realised that we can run 100Mbps with less than all cables before I watched this. Sure enough, pin 4 is coming back disconnected. All the other wires are good. Not the point of the video, but it helped me diagnose the issue 👍

I've been using 100Base Ethernet cable splitter pairs quite successfully for years. Yes, they work the way that your made yours. Thank you for explaining important considerations, limitations, and how they work! Here's why I use them: A good application for a 100Base Ethernet cable splitter is in a managed network that has Mode A PoE clients located in extreme temperature environments away from a local power supply. Although weatherized industrial PoE-powered managed PoE switches are available for use in such applications (e.g. PoE security cameras, especially where you have a cable to one camera and need to add a second camera nearby), the cost of these switches is much higher than the indoor switches in your links. Adding a managed switch can add additional maintenance needs (unless it is an automatically maintained network, which can also drive up the cost of the switch) and it adds another point of failure (including attracting possible theft of an outdoor switch that costs more than a the equipment connected to it). The passive cable splitter pair never requires maintenance, it requires no power, it is compact, it's extremely reliable in harsh environments, it can consolidate network device surge protection to one end, and it's very inexpensive. For 100Base Ethernet Mode A PoE, it just works and keeps on working.

That physical diagram between the garage and living room was perfect and made everything extremely easy to understand. I'd love to see more like that in the future.

Even back in the 90s I was able to buy working 10Base-T splitters that properly split the pairs to yield 2 connections. First supplier in mind was BlackBox, supplier of many amazing doohickeys for various types of serial and network connections. Nothing at all new about this stuff. I even had the occasion to split jacks on a single pull, as you demonstrated. I punched 2 pair into one jack and 2 pair in the other at both ends of a single CAT5 line. Done properly it worked like a charm for 10Base-T and even 100Base-T with enough twists per inch cabling. BlackBox also made wall jacks for this purpose, where all you had to do was punch the wires the same way on both ends as indicated on the jacks' punchdowns. I had a cabler test one of my own such connections with his Fluke, and they both tested okay for 100Mb, but that's not the same as two full connections lighting up all eight wires at once. I'm sure such a contraption wouldn't rate anywhere near good enough for 1Gb, even with great care with the tight pair twists in CAT6e. In the installations I directed I made damn sure to use professional cablers, good cable, good jacks and blocks, and tested-to-spec 568B connections. I always pulled extra, so need 1 but pull 2, 2 pulls 3, 3 pulls 5, etc. I also only terminated 568B, even for phones. Our phones were 4-wire links, and with either 568A or 568B the 2 center pair tracked for 4-wire phone systems. The jacks we used were also shouldered to properly hold either an RJ45 or RJ11 or RJ14 plugs. We used those lines for Ethernet, telco, and even serial with RTS/CTS and even a few times DTR/DSR...I wired my own RJ45 to DB9 and DB15 connectors for such things so I could use even 568B patch cables for serial printers. Those were the days. I'm surprised anyone sells such crap as you found. The plans for proper Ethernet splitters are still out there, and aren't even that arcane. I'd be shocked if there weren't already PCB prints ready to go with minimal case requirements. You could even build a hub or switch into a case of that size, provided it could also pull power from maybe a USB. The trick then would be whether the network switch on the other side permits switches or hubs, which in any business office they SHOULD NOT without an exception process through the networking owner. No secret guest connections.

As a teen during my LANning years, the staple LAN was the 'Organised Chaos' one held by two brothers who'd attended the 'Springbok LANs' before that. Starting out with building their hardware etc, as a cost-saving measure they would run a single CAT4 cable from a hub or switch to a given table, intended for only two computers. In this way they were able to utilize only half the cables to support 100+ 'man' LANs pretty quickly, which you can imagine in the early 2000s was still a pretty significant cost-savings for highschoolers.

As someone still occasionally having to deal with the "proper" splitters, I can tell you they've been around for ages. And they're an absolute nightmare. Because the venn diagramm of people who use these, and people who don't document jack shit in their network, is perfectly aligned. Oh and also, finding replacement ones for situations where the customer absolutely does not want a better solution (because why would you?) has become a giant hassle, because everything is saturated with the "fake ones" as dropshipped e-waste. Thanks for the sponsor by the way, that particular industry absolutely needs to become bigger.......

This video's sponsor looks like it helps to build many of the experiences I hate about trying to shop online.

As an electrician, I've always used (network) switches for connecting devices, however, the splitters work great for use in lighting control devices wired with Cat5E. Send power to a power pack module then Cat5e to a sensor or wall switch or another power pack. Splitters started coming with ceiling occupancy sensors awhile ago making installation easier.

bro i love how in every video this man makes a perfectly smooth segway into the sponser

The splitter you constructed is how the legitimate splitters are wired. They would often have a cabling diagram displayed on the top of the splitter. It was useful when things like switches were more expensive or you needed that one extra port in a location without needing a powered device. It's like the Amazon stores have thought 'oh yes, we can replicate that product' without understanding what it's actually doing.

A basic splitter should work as a 10/100 Mbps passive hub. I don't see a reason why connection fails altogether. Maybe there is an option in the network adapter settings that enables 10/100 Mbps mode compatibility.

While working in the business of networks and telecommunications I can confirm he's right. Those fake splitters had a use back in the days for some connection types, like an analogue telephone line or even ISDN lines. But it's really no use in computer networks. You'll need a real splitter like he described in the video. I also want to comment that it's a good sum up of the topic even for people not having a deep insight in networks. 👍🏼

2:39 It'll also lower the impedance presented to the headphone amplifier quite significantly if multiple low impedance headphones share a single headphone jack (assuming all headphones are connected in parallel); this could cause the amp's protection circuit to kick in or (if there isn't any protection) damage the amp.

Those devices are actually a gold mine for DIY electronics projects (non-ethernet). I recently used a lot of them to split multiple signal wires very cheaply. Ethernet cables are so cheap and they provide 8 wires inside that can be used for anything.. and those devices provide a very nice solution to duplicating the signal

Ridiculous that LTT is accepting sponsorships from dropshipping websites now.

Security installer here...there are versions of this that work. We use them (on each end) to allow 2 IP cameras to be run off '1' wire. (It's obviously two wires from the appropriate ends). As Linus mentioned in the video, you can get 100mbps with splitting. Which is WAY more than you need for a single IP camera. Works great if you need two cameras on a far end of a building, you can run just a single cable for the main trunk.

We use this Y-cables to quickly wire up the CANbus in our machines. It works great for this type of network topology. When you reach the last device on the bus, you can use the second half of the Y-cable to plug a RJ45 connector with a 120 Ohm resistor in.

A new thought occurred to me. I have actually used this successfully. I do remember reading that it technically violates the ethernet spec, primarily in that it may introduce crosstalk in very long lines, reducing the 100 meter maximum. In practice, I’ve used it to about 25m. Ad in most hacks, your mileage may vary.

These are used sometimes in Industrial applications where there are simple analog signals (24v power or maybe a digital IO or a 0-10V analog Signal) running over an RJ-45 connector. Then there are some use cases where these are practical. Like let's say you have an analog pressure signal that needs to be read by 2 different sources simultaneously.

These used to be very common (the correctly wired ones). A lot of older offices were wired up with far less structured cabling than we would do now. Worse yet some of it was probably CW1308 for phones. As more and more devices needed connecting up this became an issue, particularly when IP (and later VOIP) phones became more common. One solution was to use a pair of splitters like this to double up your infrastructure. Yes it was janky but it was also MUCH cheaper than re-wiring a building and didn't disrupt the people working there. Similar looking devices were also common on digital PBXs which used cat5 cables terminated on RJ45 ends but used entirely proprietary signalling. Some of these would actually have worked with the splitters you bought too because you could set up the live pairs on the PBX and phone so that each phone only used one pair and ignored the rest.

Actual Ethernet “splitters” do exactly what you did, and split 4 along each line. And I have seen applications where it was the most practical solution, where we had a buried line under asphalt and needed to have two physically separated connections.

At 3:10 they forgot to talk about hubs. And about the "The transmission pins on the sending device need to connect to the receiving pins on the other end" part, most network cards allow to switch the RX and TX pins internally automatically (or when did you last use a crossover cable to connect two devices directly together?) 😉

Back in the olden days (mid 2000s) we had loads of these in the company server room. We didn't have enough ports in our rack and these were everywhere to allow more low speed devices into the patch panels

I'm glad you're doing more content like this... Useful to send to my less technically smart family when they ask about junk like this.

The only time we used a network splitter was at school with several computers, where we could translate our written programme and copy it over to the roboter. To make sure that that only one computer could get access to one roboter, they used a splitter with a switch to select the current active connection. Anyways, quite informative eventhough would have guessed so already when I just think about IP's. Honestly didn't think about the DIY method though.

In the very early 2000s, my family wired up ethernet through the walls in their house, but we didn't put in enough copper for later expansion, so when the day came that we wanted to put two computers in one room, we tried doing this with the single run going to that panel. In theory it should have worked, but when we actually tried it, we found that one machine or the other would link up at 100 full duplex, but the other would consistently connect at only 10 half, and it would flip randomly back and forth if you cycled the connections. I've never been sure whether this was due to the inferior isolation between pairs in CAT5, which I should mention wasn't even the E variant at this time, or if the network cards were using had inferior transceivers, or if we just plain wired it wrong and didn't notice. I had heard at one point that it was a violation of the signal spec, and it makes sense to me that this would produce too much crosstalk between pairs, but that might just be one of those things that doesn't officially work, but in all practical cases does. Certainly, there seem to be plenty of comments from other people suggesting that this used to work reliably for them.

I'm surprised it didn't work tbh. Maybe because of the switch, or maybe windows has disabled csma/cd by default now under the assumption that all ethernet connections are switched nowadays, but once upon a time, home networks used ethernet hubs, not Ethernet switches, and these genuinely did exactly what this splitter here does, only with even more ports

Worked at a company where we used to use splitters back in the start 2000es. At that time 100mbit was the standard and REALLY fast, so splitters were a very useable method to use a single installed cable for two computers. I think we might even have created them ourselves 🙂.

This is actually was done in older environments. At my work, in some of our older horizontal wiring installations are setup this way. the cat 5 wiring uses a Siamese type of wire where 2 of the 4 pairs are separated in their own sleeve but bonded together in parallel. Then, If a particularly area need two ports, each sleeve gets its own connection to the switch. But again, your limited to 100mb on each port. It also can be setup normally where both sleeves are patch together. you will then get gigabyte speeds in that case. We are slowly trying to phase that type of wiring out of our building(s) the patch panels are too big and bulky

I remember when cat5 first came out and the company i was working for was going around upgrading people's old coax and one I cant remember with like BNC connectors and even some 25 pin cables in short runs to newer cat 5 setups. The key to the cat5 working is the fact each colored pair is twisted at different rates effectively making each colors run a slightly different length and would have very small but detectable lag time differences as well as resistances. This is how we tested runs were done correctly, the tester ran a timed signal along each line and if it didn't get the pulses in the right timed order then the run was a fail and we needed to pull another line or resolve the issue. Which was typically an end terminal was punched down wrong because for some reason the guy related to the boss who was color blind was allowed to install the wall jacks. (If I'm wrong in this please forgive me, this is how it was explained to me by the bosses nephew that was my partner for many jobs. funny how when it came time to reduce head count the only guy not related to the owner was the first to get canned)

Did Linus really advertise for a Dropshipping buisness?

It was actually kind of shocking to me, earlier in my career (10-20 years ago) how common splitting a CAT5 (or even older) cable in half is in retail environments. Tons of connections at front of house cash registers with the POS on 4-conductor data, often with the other 4 being used for POTS phones. They're still out there being used.

I had a Radio Shack splitter. It did work, kind of. When used with 2 devices, if either of them were using network a lot (such as downloading newest Ubuntu), collision will occurs often and the speed will drop a lot. But when there's light traffic, those worked well. I connected 2 networked printer with Radio Shack splitter and didn't have any issue with that splitter.

I used to run a PSTN telephone and an Ethernet connection over a single CAT5 cable between two rooms using a similar splitting technique; 4 wires used for each connection. Worked like a charm.

Ethernet was actually originally designed for this kind of thing to work just fine! If you're as old as I am, you may remember seeing computers wired up with 10BASE-2 or 10BASE-5. These older Ethernet physical layers allowed a group of computers to talk over a shared coaxial cable--each computer just taps off the cable at some point or another and they all use CSMA/CD to avoid talking over each other. With twisted-pair Ethernet (aka every kind of Ethernet we've used since then), however, you need at bare minimum a hub--it's just not electrically designed to be used the same way as the coax flavor. This does come with advantages--it's harder for one fault to bring the whole network down, and each computer can be freely plugged in and unplugged without disturbing the others.

The most stupid thing about these splitters is that the Chinese factory knocking them out could just as easily separate out 2 twisted pairs to each port, as Linus did. It's bizarre that they don't.

About 4 years ago I had ( a very uncommon) situation that couldn’t be solved just by adding a switch so I built a couple of splitters like the ones Linus made on the second half of the video. In the laundry room I had the ISP modem > router > 16 ports switch > patch panel . Obviously The latter distributing the connections around the house One of those connections went to the main bedroom where I had an Apple TV AND a TV decoder (rom the same ISP supplier. There was only 1 Ethernet jack below the TV. The problem was that the I really wanted to connect by wire the Apple TV and the tv decoder needed to be connected to a “special” port in the modem independent from the “regular “ Ethernet ports. So then the splitters were used to do two connections: from the special modem port to the tv decoder and from the switch to the Apple TV. As you can see Using a switch was not a solution whereas this bizarre thing solved it.

These splitters do make sense if you break it down a certain way. For example, if you deal with gaming and have multiple game consoles, you can theoretically connect 2 devices with the splitter. Since normally you would have one screen and tend to power off the console not being used, the console that is turned on should pick up the internet signal and work. You can buy a switch, a router, or what ever but at the end you have one tv/monitor and only playing with one device at a time.

The "DIY" version is also available commercially and has been for years. In times when 100mbit was still pretty much standard I have been using them for Mir than one customer. If you image search for "Delock Rj45 LAN Anschlussverdoppler" you can find a model that shows the wiring on the casing.

Properly made splitters have existed for a long time. I've used them and had to make them in some cases to repurpose old building wiring. In some cases, because it was CAT5 (not e) cable wired for phones originally, using a RJ45 to RJ11 adapter was........ fun.

These were useful back in the day in datacentres where cables cost a lot of money for low speed connections, or I think E1s (European T1s). Kind of same idea as using bi-di optics these days. Wouldn't use these though :) - I do love the UniFi Switch Flex Mini for these :)

Well i found one from old days laying around, but it really safed me setting up my new 3d printer as i had no cable that was long enough so i just took 2 3m cables and combined them with the old adapter and done 6m lan... Not how they say they should be used but a good use case

This is actually build pretty robustly. Shame that all the engineering time went into the case design and non went into electrical design.

It seems like the documentation for the original splitter is wrong. If they've wired it like described, you'd only want the adapter on one side. A switch like you connected to would likely disable the ports since you effectively connected them directly together. CSMA/CD would effectively mean the client devices are connected to a passive hub like we used to do back in the days of vampire taps. Your link speed would probably negotiate at either 10 or 100 half duplex, and overall performance would drop through the floor depending on how much traffic you were trying to push, but it *should* work. You could even keep branching them out as far as you wanted, but performance would drop for every additional device you added to the tree.

Linus, im so glad you actually made this video. This is something every techie should know as its been around since 2001 and its very handy to know and can solve some very difficult issues for alot of people. For instance, Ive been using this method for many years for an underground cable issue where I have 2 underground cat5e to the garage. My modems are in the garage, which is 300 feet from the house. I have 2 seperate modem connections for 2 seperate networks serving 2 seperate things. That being said I added a pretty large security camera system and I absolutely need all of a gigabit connection and an air gapped network for the nvr in my house. So I have my modem connections to my routers in my house on a single cat5e split to 2 100baset connections. My internet speeds are only 100mb max per anyway so instead of trenching 324 feet for a new cable run I can run everything full speed without trenching.

Here in the uk we have a splitter product from Haydon that also enables POE. I use them for my cctv installations where I need two IP cameras to work from a single Ethernet cable run and they work a treat.

For nostalgia and a complete picture: in Europe similiar splitters were common to split a 4x2pair wire into 100Base Ethernet on pins 1236 and ISDN S0-bus on pins 3456. As ISDN was a bus you also could actually run up tp four devices (i.e. telephones) simultaniously on such "split rivers", but only middle pins 3456 were ever used.

4:32 perfect safety shown by Linus, using a mini circular saw and cutting TOWARDS his hand, and getting about 2cm away from it.

I am an installer and have done this reliably because some customers won't pay for additional cable runs and this allows a managed switch to "see" each device which can't be done using a non managed switch. You can also use the other pairs for digital phones and other equipment if it is needed. Two pair is still better than wireless.

Not all splitters are wired wrong. I bought a pair for exactly this purpose and they worked just great. We even run proper PoE for one of these connections over the splitter (because they use the same wires). Older semi-official PoE uses spare wires and won't work over the splitters.

6:57 "100 Mb is so slow!" as sit here, with 50 mb spread out across 4 family members, 3 of whom are incredibly tech savvy and all need high speed Ethernet

To be clear, whether a signal is analog or digital doesn't influence whether a splitter can work. The deciding factor is whether or not its a two-way protocol. To give an example, the DMX-512 protocol, can be split just fine (in fact passthrough is the basis of the whole protocol). It goes a bit further than that, there are two-way protocols that can be split just fine like phone lines, it all depends on the design of the protocol, whether or not its sequential/serial in nature mostly.

I used this product when we switched from from vdsl to cable internet. The connection point of the cable connection was on the other side of the house so the existing cat E wiring didn't make sense anymore. There was one cable available near the new router that went to the other side of the house so we used the splitter to connect the media PC and a wifi access point both with 100 mbit. We got the two splitters from the local computer shop and they made sure the wiring inside was correct. Wired pc and good wifi coverage for 10$ without using a switch. Last year we switched to gigabit fiber and then the connection point changed again, so we "properly" redid the wiring as the 100mbit really became a bottleneck.

I've used these on Schneider VFDs that use a serial/analogue based comms protocol (modbus) and an RJ45 as the connetor. They work pretty well for that application.

I'm quite familiar with this kind of splitters (the ones Linus built) -- we often used them in the university dormitories in rooms for three people that were only wired for two ethernet jacks. Split it up, boop-a-dee-doo and you've got three for the price of two. Or even four! And since the ethernet was 100 mbps back then anyways, nobody minded at all.

Thank you for the Ethernet switch suggestion I didn’t know I could get away with a real cheap one ($15) like that, I was looking on Best Buy a few months ago and they were all pretty expensive and I thought I was just gonna have to suck it up, I just have little hobby self hosted projects like an IRC and a media server and this will help a lot because I’ve been wanting to get my main pc off of Wi-Fi as I’ve been using my sole Ethernet connection for the raspberry pi I use as my media server

Back in the early days of ADSL I had a pair of splitters (and a pile of adapters) to bring both the lan side of the router, and a regular phone line using a single Cat5 from the ground to the third floor of our house. As the ADSL was sub meg speeds back then it all worked a treat. We had a hub but it needed to be on the top floor due to the very old construction of the house and how we had to route the rest of the lan. We only ditched the splitters once the phone line was no longer needed. Those Amazon splitters are super janky, I can see no purpose for them other than simply to generate e-waste.

This is something I figured out the hard way 20 years ago when I had to figure out a ethernet-based internet solution with one wire for me and little sister's PCs. My ultimate solution was to connect my little sis's PC to mine and get internet that way her for PC. It was slow, but we did manage to play games online at the same time, especially since we went from dial-up to cable modem. Good times.

You used to be able to buy splitters wired exactly like the one that you made. I used them a lot in the early 2000's when network switches and hubs were too expensive, and most house wiring only had one cable to each room. Back then everything was 100BaseTX anyway so you weren't losing anything. The brand I used to use had the wiring diagram on a label on the side of the splitter so you could make sure you had the right ones.

I'd love a similar video about power-line adapters for ethernet. Currently running one from my router to my bedroom and don't really seem to notice too much improvement than over wifi other than stability.

I've known and used this "hack" for years. A fairly recent example is setting up POE security cameras. I had two security cameras going up on the roof, where there wasn't power for well over 100 ft. (30 meters) Installing POE cameras and splitting the network cable just like this worked great!

I was using the 'correct' splitters back in the 90's, the same type you made, they where available from our local trade supply. the newer style of one computer or the other was available too, but pretty useless in a corporate environment. I must of installed at least 1000 of those splitters in places where we where not given enough time to re-run new cables.

There are actually old proper Ethernet hubs from when switches were more expensive. They were used a lot in industrial applications because they were relatively low bandwidth. They did however use electronic repeaters instead of just tying terminals together. The downside is that without switching there was a lot of packets being destroyed by two devices transmitting at the same time.

I used splitters in an office setting. We had a location where we wanted some printers, but we didn't have enough ports at that location. Back then, 100 Mbps was the norm, so using a splitter didn't actually matter that much.

As a low voltage installer that works with POE T568 equipment...this was a super fun watch!

Auto DS seems sus. Having the word “dropshipping” on your front page is a huge red flag to me

Linus just found out about the passive ethernet hub (layer one of the OSI model). Keep learning, Linus!

Interesting Y cable and great call out on POE as thats likely popular with IP Cams. Has anyone tested this out though with 2 machines say streaming 4K video or performing large downloads at the same time? Is there cross over talk that may become apparent via Tx/Rx errors/retransmits? I'd suspect you will need to get a cable that shields each pair of wires.

You can get from high end computer vender they do sell splitters that to work, and are normal are send and receive modules. These are extremely popular add-ons in the point of sell computers and they are preferred over switches, especially in areas. They are prone to afternoon thunderstorms. With locations like this with the power flickering off and on if there’s not battery back ups on everything, the network can get split into two networks are some people call an ARP bubble were multiple networks switches cannot see each other. The only way to resolve this is to power down all devices. All networks switches for five minutes then bring them up in the correct order. These are great connect multiple locations or remodels to one centralized networks switch. Again as you said they are 100 Mbps are 10 Mbps, which in this network configuration is perfectly fine enough ❤bandwidth for everything to work with no delays.

When I was about 12 or so, and didn't understand these concepts, I searched for ethernet splitters in order to use my Xbox and PC on the same cable. Luckily I got one that was setup in the same way as the one you made! And this was way before anyone worried about any 100mbit connections, so I would never even have noticed the drop in speed. Worked great for my usage!

Um, you know you totally can have passive Ethernet hubs, right? That box should just be a box of correctly wired diodes. See, Ethernet contains carrier sense multiple access / collision detecion (CSMA/CD) All the devices start to notice collisions, discard the data and start using random packet timings to avoid collisions. Only works in half duplex too, but that might be a function of it being a concentrated network instead of a switched or active network. The switch in the router is supposed to drop to half duplex. Probably 100baseT too, i don't know about the ones that use the whole pair set

When we built the addition to our house, the electricians offered to run and wire up all our Cat 5 cables drops (about 28 total drops). Their price was reasonable so I showed them where in the utility room I planned to put the patch panel and needed all the cables to be run to. When they told me they had finished, I discovered they had ignored my instructions and had daisy-chained all of the wiring between each drop as if it was telephone cable. They adamantly refused to fix it insisting that this is how they do it every time and no one had ever complained

The comments I saw most on-line were from people who claimed they didn’t work and had only bought one of them. I never understood why they were not always sold as pairs. Having said that, I work in electronics and I read descriptions. I don’t take anything for granted.

It's interesting to see this. We actually had a few of these at a doctor's office I worked at years ago. They added patient portals to each office and there was only one Jack available. Rather than put switches in we just did exactly what you did there and split out the connection. Worked fine

If I remember correctly from my CompSci degree, these things (while still useless) should work if you plug in just one, as they function exactly like a hub and thanks to backwards compatibility of ethernet with CSMA/CD (Carrier Sende Multiple Acces with Collision Detection). Have you tested this? This would've been an awesome inclusion in the video.

I must admit, at first, I thought it was just a tiny hub. I know you can't have multiple devices sharing one cable. EDIT: 5:26 - That's the exact same switch I have next to me now. It connects the router, downstairs PC, downstairs printer and upstairs switch together. The upstairs large switch connects to downstairs, another wifi access point, server, and upstairs rooms :) It's a good little switch, it's been working flawlessly for years. What's better, it's made of metal and uses basic green LED's. No ugly rounded plastic shells in this house... Everything is metal, and beige, or navy blue.

I would assume the main issue is communication. With audio and power, it's mainly a one-way trip. With internet, the connected device is communicating back to the router and the router to the tower. You couldn't just funnel or copy the signal across 2 cables because it goes both ways.

That "splitter" device might actually work if you set your network ports to half-duplex. Since half-duplex would turn on CSMA/CD, it would be a junction hub. I've not used half-duplex in years, so I'm not 100% sure. But if I remember correctly, it should work. Also, split pairs have been used for year in telephony. 4 pairs meant that multiple 2-wire or 4-wire analog phones could go down a single Cat5. Made wiring PBX systems to office pods quicker and cheaper. Of course, VOIP made all that obsolete. And I absolutely would not go back, VOIP is superior in almost every way.

Back in the early 2000s these adapters (correctly wired ones) were used a lot. Gigabit was no requirement yet and those adapters helped to use one cable for two devices. E.g. digital phones (ISDN) + Ethernet could be sent over the same cable. Even today it can be useful if you (for some reason) need an analogue phone line and wired network but have only a single spare cable. I could use a pair of those adapters (still from the early 2000s) to connect my phone and my computer although there was only a single ethernet cable available.

Only two pairs of cables are necessary for 100Mbit Ethernet. Each cable has 4 pairs. So you can put two 100mbit lines through one cable. OR For serial RS485 only one pair is used, but sometimes RJ45 cable is used for this.

Splitters like you made (1,2,3,6 and 4,5,7,8) had been commercially available pretty much as far back as UTP and T568B has been around. It's the same concept as the 2-line POTS phone splitters that you can still get. It used to be quite commonplace to run one CAT3/5 cable to each desk using pins 1,2,3,6 for ethernet, pins 4,5 for POTS line 1, and pins 7,8 for POTS line 2 in office settings. Although you would usually split out the wires behind the scenes (gangbox in wall, panduit, or cubicle kickplate) to separate registered jacks rather than using a "dongle" like your splitter, but the dongles did exist to perform the combining/splitting.

It seems to me that such a splitter *would* be useful for PoE cases where the Ethernet cables are used solely for power. Also, I wouldn't say that splitting doesn't work for Ethernet because of analog vs. digital but because all endpoints for Ethernet are *active* (and not passive like headphones). You'd have similar problems with analog signals if you tried to use a headphone splitter in reverse as an attempt to mix two audio signals; ultimately the problem is that one device is trying to set the voltage of a wire to X while another device is trying to set the voltage on the same wire to Y, making nobody happy.

Hey Linus, nice video. Thou I want to clarify that there are in fact many real spliitters on Amazon that are wired just as you hacked your splitter. I work as a electrican in Germany and can tell you that I see those splitters quite often used. Especially if you have one outlet and want to connect a landline phone as well as a printer for example. If you have a bigger infrastructure and don't want any devices which would need extra power, could lower your network security or are a point of failure and you don't need the transfer speed (e.g. phone and printer) it's for sure a valid option (e.g. kwmobile, they even printed the wiring diagram on the connectors)

A potential clandestine purpose for this device is to be used as a V-Line network tap / passive tap. Disable one of the blue or brown pins carefully to force the target device to autonegotiate at 100mbps. Insert the splitter device in-line with the device to be monitored, connect a third machine to the second port of the splitter, force the third device's interface up without an IP address, and manually configure for 100Base-T (no auto-negotiate), set the interface into promiscuous mode, and capture your packets. The goal is to not transmit any packets out the interface on the third machine, but just monitor the network. Although you may only be able to capture one side of the communication..... You could even connect it to a small portable Raspberri Pi and connect back wirelessly to the raspberri Pi to capture packets of a device remotely, but now we're really getting into some Mr. Robot territory here. See, this device may indeed work with three devices connected, and may be quite useful to the right group of people.... so it's perhaps not totally useless.

Im so glad I had a friend who called them "ethernet switches" so when I needed one years later, I didn't search for "splitter".

Brings to mind the old days of using co-ax networking. Just add a double adapter fitting to add another PC. It was much easier “atleast in my experience” to get working at times also much easier for long run’s. Used to have family living next door so we had a co-ax line set up linking both houses into one network.

You can actually passively split 10Base-T connections, but it requires a set of diodes between each port and the trunk. Basically, the diodes cross connect the transmit of each computer to the receiver of the other. And since this is technically a passive hub, the systems have a built in technique that prevents them from talking over each other. I used to have one that I took all over the country with me as I worked on system installs.

Retrofitting an antique house, I did co-opt the telephone Cat-3 wiring to use one pair for voice, and the other two for RJ-45 for networking… This was well before Gigabit or even 100-T was really a consumer thing. As good as dedicated cat-5? No, but for sharing a single DSL supplied router to the household and peer-to-peer? Just fine, without having to do a few thousand dollars worth of chasing wires through finshed (and ancient lathe-and-plaster) walls in an occupied house.

Oh those were known as "collider" splitter. They could work some time ago, when the devices were much less smart. They worked as a dumb hub (not switch!) by hoping that two devices won't transmit at the same time, and if they did it caused a "collision" so the devices detected it and tried to retransmit later. The difference from an actual hub was that a network collision only meant the packet won't go through - or only one of them will (higher numbered ports got a priority). Whereas this plug sends reverse voltages during such an event relying on built-in protection to save the devices from being fried. Of course if such protection was not built in, some very cheap very early devices could in fact die, although more likely just failed to function. Nowadays devices don't expect dumb hubs and re-transmitting a thousand times to local network at all, and a discrepancy is seen as a network connectivity loss. Sometimes you can configure that behavior in driver configuration and OS configuration, but I don't think Windows is capable of that anymore. disclaimer: I'm a sysadmin but not a networking expert in any capacity so what I wrote may be not very accurate - don't quote me, I never used one of those - resorting to Linus's 100MB splitters in dire need. In fact, in Russia old informal networks were wired in such a way because most of our houses were built in USSR only expecting at most a 1-pair phone cable to each flat, and a single TV and radio cable for entire house, so in most cases there was no space for additional 30-something cables. Switches were also too expensive and prone to being stolen to put them on every floor, especially if there were like 2-5 different internet providers in the same building who couldn't use each other's connection. Pulling a cable often involved a lot of oil and considerable force. So branching.off an existing cable was often the only viable option. Until a decade ago internet speed more than 100Mbit was not even an option most providers would offer.

This is one of those things everyone who did networking and phone systems in the 90's and early 2000's knew of and did. The catch was when you encountered someone who had split out the pairs (or worst of all randomly selected wires) in a custom way and you had to test or trace them out. :-( lesson learned from this pain. Leave notes understandable by the next guy on the inside of the panel or on a label.