Hi,

When I invite my friend to my party, he gets a popup. If he accepts I show up in his party. I don't see him on my screen though. When I start a mission he enters the mission, but I don't. I cannot start another mission either. Tooltip on the start button says  Vote in progress.

When he invites me to a party I don't get a popup.

Edit: Tried portforwarding and a VPN (same as my friend uses). Nothing works.
Same result if I route my internet traffic through his VPN.

So it seems local, and not a routing issue...