Going through a lot of issues myself but if you want a little help finding where it failed. I suggest starting in the editor and looking at the log data while testing it. Once you attempt a connection quickly stop the game and then scroll to find error. You can copy and paste the information into a note pad and then do control F and that will allow you to search key words like server and error to get an idea at what point it failed. After that just google what the error mean and good luck. My issue was I had to compile on 2 different devices and the auto save would cause the game to technically be to separate builds.