It's ridiculous and amazing to me that we still don't have a definitive list of all of the UDP/TCP ports that need to be opened to run this game server without leaving yourself completely vunerable to the internet. I suppose they believe that in this day and age no one is running behind firewalls or routers. What naive, fantasy world are they living in?!
That being said, you may want to have a look at this. This seems more for the client than for the server, but you may want to try opening all these ports for UDP and TCP.