Can't Create server. why? :(

[HomerMix]

Yesterday I wanted to fly with a friend. So i tryed to create a server but it doesn't work.
On the screen where you can choose the server name and descrition, i keep getting "server could not connect to steam" when pressing ok and get back tu the menu.
I have no problem joining online servers appearing in the list. Direct connect to my friend using his external IP and port ended in a timeout.
I disabled the firewall and don't use a router.
I tried both internal and external IP in my NET settings.
Currently i'm running the latest beta patch. But i couldn't create any server before either.

Edit: When trying to create a server via the lobby i get the same error.

Any Ideas what could be wrong?

[HomerMix]

reinstalled cliffs of dover, still no luck.
First i get "connection to steam lost - Exiting" and qickliy after that "server could not connect to steam"
Steam is still running BTW and i'm still logged in.

I'm short of ideas. Any Help would be apreciated so i can play with my mate.

[Ataros]

Steam needs many ports to be open (check Steam FAQ for servers).

Maybe your provider placed you behind a router or blocking some ports. Try talking to them with the list of ports taken from Steam FAQ.

You should be able to set a server in Lobby anyway though. Keep trying.

[HomerMix]

Well, setting up servers in other steam games such as Counterstrike Souce and HL2 Deathmatch works fine. So there must be something messed uo in my clod.
Any idea what i should look at?