I've got a problem with it. I can only be a client. If i'm host - nobody can join my game.
My friend have the opposite. He can only be a host. He don't see any games in list at all, but he can host & everybody see him & can join. We both have patched our games with the same english patch.
Is it lag or smth?

You:
Check your firewall and/or router settings (portforwarding).
http://forum.team17.co.uk/showthread.php?t=7171#7.4

Your friend:
He has to set his timezone in Windows correctly.

Or you can download IP Over 2.0 from Blame The Pixel (http://www.blamethepixel.com) if you have cable internet or if Bonz's suggestion does not work.

Bonz is right about what your friend has to do.

Plainplane :)