Can't find friend on the same server.
Is he set to invisible? Are you able to add his username to the friends list? Did you double check to see if you had the correct username?
Get into the same party as your friend and right click on his name and click ‘’join server’’ (I think, could be named differently). GW2 has since about a month ago mega servers. Which means it doesn’t really matter what server you are in, except for WvWvW.
Character names are game-wide, so it doesn’t mean he would be on a different server. Could be the same server or a different server. You should be able to add your friend’s Display Name (make sure to include the numbers) and interact with him no matter where he is (at least chat-wise). If he is in a different region (NA vs. EU), you would not be able to party up with him. The exception might be PvP, I’m not sure.
Character names are game-wide, so it doesn’t mean he would be on a different server. Could be the same server or a different server. You should be able to add your friend’s Display Name (make sure to include the numbers) and interact with him no matter where he is (at least chat-wise). If he is in a different region (NA vs. EU), you would not be able to party up with him. The exception might be PvP, I’m not sure.
You should be able to whisper him, with his account name and see the above post – good info there.
You say you can’t invite/join. Does that mean you click on his name in your friend’s list and no invite option appears? That if you pull up a party panel and type in his name that it doesn’t allow this? Does it mean that he can’t do the above with your name?
If neither of you can invite the other then it sounds like a bug.
Well, it was a flaw on his side. Thanks for at least trying to help !