I setup a self hosted dedicated server and we have been playing on it for a few days.
The server crashed for the first time today while we were playing.
I restarted the server and was able to rejoin no problem, my friend though, the history of the server shows greyed out/offline.
I've run the FAQ connectivity commands and they showed correct from the dedicated server, I have to assume since I can rejoin fine its on his end and possibly the dedicated server.
Friend reinputs the code, and near instantly says unable to find server, the first time we both searched yesterday, it took a noticeable period to locate so instant response to not finding the server seems a notable thing.
They try to join me via steam friends, gets a message server not found.
They are not very networking technical