Cant Host game no matter what i try :S

Me and 3 other Friends bought the 4-Pack of the Game on Steam.

All 4 of us have opend all the listed ports
UDP 1200 (used for friends service)
TCP 27000-27050
UDP 27000-27050
TCP 7777-7780
UDP 7777-7780

We are 110% sure, we have trippled checked this, we opend the ports on our Routers and on our Firewalls.
And STILL neither of us can host a game and invite the others to it. :S
We really wanted to play 4 player co-op Blitz but it seems impossible, if anyone knows what the problem is please help us out here!

Have you tried to deactivate your firewalls during the match?

Problem is we cant even get into the match, its as if it dosnt excist for others.
And yes, we tried deactivating our firewalls aswel. dosnt help at all.

Have you tried it over Hamachi/Tunngle with a lan game?

Could do that, but should i really need to resort to third party applications just to play the game with friends? thats really really bad imo.

No one else knows a solution?... well its impossible to host in this game.

Are you able to host Crossfire matches?

I'm having the same problem, I can't believe noone knows a fix?

A buddy of mine managed to rig it up to host Crossfire/Blitz games. Not sure exactly what he did, but I think he commented about having to forward more ports than the ones listed