Dang. I was hoping it would have worked for you. As far as how it’s worked for the three of us, usually the challenger is the one in arcade mode and sends the challenge. Then the challenger stays in the menu while in arcade mode. The one receiving the challenge I believe is usually still in the main menu. At least that’s what the three of us are remembering. I wonder if there is a network setting/port that may need to be opened in certain cases for some people behind certain firewalls/routers.
What I know is that it takes a while for the “challange accepted” message to arrive. Once the friend accepted both games close the menu and get yo the main screen, or arcade (but with unmoving characters) in this last attempt, then after a while we connect but not really. It’s weird.
If you have trouble playing online games, try forwarding the UDP ports 9991 and 19900 in your home router.
Most players should not need to do this, but some routers work differently and will defeat our NAT punchthrough code, in which case manually forwarding the ports may work.