yeah this simple analogy made this concept so simple to understand.

The private key and public key use different formats (and the private key is larger.) While it might be acceptable from a security standpoint in some scenarios, I wouldn't expect it to work in practice with most software. There are several good Stack Exchange answers about this if you do a web search for your question.

@@NerdOnTheStreet thank you for explaining the difference. so i can look for the length

Because Nextcloud is open-source. I'm actually not a fan of the Nextcloud developers (they tend to think they "know what's best" for their users), but Filerun being proprietary makes it a stain for me, as well as it works.

@@NerdOnTheStreet How safe is it for me to store a copy of my private SHH key on nextcloud if I use a provider? I rent a room in a house with 2 other roommates and if my PCs/gear were ever stolen, I'd lose the key. granted, my server is a Pi4, so that might get stolen, too. That is one reason I don't want my own Nextcloud on my own server.

"at 10:50 what is this supposed to be? Entering via root?" - Yes, that moment is logging into the root account of a server that is still configured with password-based authentication. "you didn't even say if it belongs to the server or to the computer it owns." - Servers do not "own" computers. I don't know where you got that idea, because it wasn't from this video. You can also deduce that if I'm on a client computer and I'm SSH'ing into something, it's not the client computer... because why would I SSH into the computer that I'm already on? "it found no ERROR No such file?" - It seems like you messed up the formation of this sentence, but you provided an incorrect filename or path to a command if you're seeing that message. If you're sure that the file path is correct, then you may be running a command meant for the client on the server (or vice versa). "All the procedures I tried to do according to the video" - You most certainly did not do the procedures according to the video if it's not working. This is a very basic process that doesn't change much between distros or over time. "I have no other option but to give up and use another server instead of SSH" - You're going to throw away a physical server because you can't log in with SSH? Or do you mean "use another authentication mechanism," like a password? SSH is extremely common and there are many resources about how to set it up, so please do not insinuate that your failure to follow my tutorial means that I have deprived you of the ability to use a server.