Friend of mine unable to login to servers, "Try again later,"

Last night, a few friends and I got together to make new characters. Three of us were new to the server, so naturally we had a few people have to install the WOTLK client. One of my friends had installed the previous night and played from levels 1-10 with me for the first hour or so, so he could get a feel for the game. However, when the five of us got together to play, my friend got an error message each time he tried to log-on. "Cannot connect to the server, please try again later. If this issue persists contact customer support." Naturally, we routed for way to solve this, things we checked include -
-Changing properties in the Warmane Folder
-Double and triple checking .WTF for the server IP
-Making an alt account to see if the account was banned for some reason or another
-Verifying the Firewall allowed Warmane through
-Attempting to portforward

Current he is trying to contact his ISP to check with his connection, but I doubt this will work.

Last night he managed to get on, but only after he reinstalled the entire game and the files. So I can safely assume it is not his internet. But after crashing in a deadmines run the issue arose and forced us to log off for the night.

My question: Is there anything we have no tried yet that could help solve the issue?

Thank you for reading
-Rolorius & TheCanadianBud