ok, I looked a bit around on the wiki page, and I can say, that I already know what to do in my router setup.
I play alot games on the internet, and also set up servers for the games. Even Teamspeak servers a.s.o...
Some of the applications also need TCP and UDP ports to be mapped correctly, thats no problem with my router (i use an old PC with Linux on diskette, Fli4L, very easy stuff, and very nice, without hard disk, so there is hardly no sound from the router)
Checklist:
Downloaded LFS, tried to set up a server, not possible to connect.
Deleted LFS, downloaded again and installed, tried to set up a server, not possible to connect.
Downloaded dedicated server LFS, set up a game, not possible to set up a server.
Ports 63392 and 29339 are opened and mapped to my IP, TCP and UDP.
I left the settings all default, and opened my server for about 2-3 hours, no chance to get on it, or see it on the server list.
Even no chance to connect to the game via IP.
Playing on the Internet is no problem...