I tried i yesterday and also today. Every time i created some mission or someone else did it, other users were unable to join. Only thing was that game just wrote unable to connect and that was all. Does anyone have same troubles? Did anyone play coop today or yesterday? And is this often? Because i am new and these were my first tries to play this.

Thank for reply.

make sure that it is allowed though your firewall/s also make sure you have the game patches to the latest patch

on a side not make sure your graphics card has the latest drivers