I've had the same problem at a friend of mine when I was at a small lan party trying to host. And a friend of mine's been trying to host for a while with his speedtouch router, same problem.
I've forwarded the ports properly, but the server isn't stable net wise.
I'm not using a wireless connection.
Sometimes players can find the server and sometimes they can't.
I've even had players who joined the server and spawned and walked around but they timeout almost instantly.
And finally my routermodem's name is "Multimodem Thomson Speedtouch 780wlt".
Edit:
I've also tried setting it up in DMZ mode. I think I did it right
Edit:
Oh and the firmware is a custom firmware modified or made by Telenor.
I've forwarded the ports properly, but the server isn't stable net wise.
I'm not using a wireless connection.
Sometimes players can find the server and sometimes they can't.
I've even had players who joined the server and spawned and walked around but they timeout almost instantly.
And finally my routermodem's name is "Multimodem Thomson Speedtouch 780wlt".
Edit:
I've also tried setting it up in DMZ mode. I think I did it right
Edit:
Oh and the firmware is a custom firmware modified or made by Telenor.