Failed to connect (connectionfailed)

Since i bought the game (it’s a week) i can’t connect to any server. It’s loading for a while and then it gets back to the main menu and it writes “Failed to connect (connectionfailed)”.
I really don’t know what is wrong with it. Today before and then after the update i tryed join on the server and it was successfull. I joined the server 2 times and then the same problem, “Failed to connect” again.
I tryed reinstalling the game, disabling the firewall and Avast, nothing helps.

My OS: Windows 7 (x86) 64-bit

Please help !