I don't know if I should be posting this somewhere else, or if anyone will read this but... I have the same error. I always get the "The specified nickname or account name is already in use. Please try using a different one" message. I'm using my server name and my server password, and I also erased that IP line from my options.ini file. Also, I opened the Firewall for both the T3A launcher and the bfme.exe (And of course, Revora appears in the ONLINE login menu of the bfme game).
However, I can't fix it. I can't log in my server. Can anybody help, please? Thank you!
Edit: Aha! Trying random nicknames fixes it. It's weird that my Spanish name was already in use but... okay. Fixed.