I've searched for this particular problem, but couldn't find answers. I'm at a student network with one centralized gigarouter. On the university network page it says that most UDP ports are closed, TCP connections can only be set up with computers at the network..I successfully managed to join my own server on TCP with two instances of JJ2 runnning. OS is Windows vista.

When I try to join a game through the internet, all servers and all versions are pinging. According to the GIP my own server is pinging too, but I can join myself

But on ubuntu/linux, the application I use for filesharing (Nicotine+) works both when uploading and downloading (to tell you about ports). I tried running JJ2 on wine, and it worked, but I haven't tested it online yet.

EDIT: I can join my own server both on TCP and internet play, but nothing else. GIP shows it's pinging.

Any help about the student network situation?