Hi all, I have already had some adventures in the past few days with my Steam friends. However, since the last hotfix patch, when I try to play with a friend from Steam, I keep getting the "Natpunch(66)" error. I have tried adding my friend on GOG and inviting them, synchronizing GOG with Steam, and even using direct connection with a code. Unfortunately, in all cases, neither I nor my friend can get past the NATPUNCH(66) error. Does anyone have a solution?
Thanks a lot, everyone.

My brother and I share a copy to play with friends who are on Steam. Sometimes only one of us can connect so if I switch over to a VPN connection, it allows both of us to connect to the Steam host. I have not tried opening ports yet but so far this is one of the only games with connection issues.