Could not establish connection to Steam servers

[jesper]

I had this problem. I solved it by allowing UDP on port 26901.
Very interesting since i couldnt find any documentation even mentioning that port. ^^
Not sure if thats a static port VAC uses or not, i have 2 servers on different ip's, and both are using that port.

Try using netstat to find out what port its listening on, if 26901 doesnt do it for you.