[Googi]

Most likely the network blocks traffic on all ports except a few specified ones.

Best advice I can give you is to Google "yougetsignal" and click on the first result. Then try entering common ports like 21, 80, 110, etc. (there's a list of them on the site) in the "Port Number" box and testing them until you get one that's open. Then go into Graal's options ----> General ----> Uncheck "Don't use UDP for data packages" ----> Check "Use fixed port for UDP" and set the port to one that tested as open. Even if it works you'll probably have trouble seeing other player's movements, etc. but it's better than nothing.

You might also want to look into Tor although I doubt that it would work for this problem.