Hello, I'm experiencing the same issue and I've been trying to fix this for the whole day now. I must say im about to give up.
I'm trying to join a game hosted by a cpu in same local network. I've made 2 rules for ports 6113 and 6112 forwarding on my router and add them to each computer regedit "Game Data Port" as the tutorial shows. I don't receive the "Port is close" error message in the game hub which is a good sign.
However, still latency issue when trying to join in.
I made sure my Firewall was not blocking, I even made a rule to force activation from ports 6111-6119 UDP and TCP.
After this, I tried with VPN TunnelBear and same config.
Same thing, can't join.
I can join others game and others can join mine as mention before in this post. Just can't if hosts are the same lcoal network.
Anyone found a fix to this since this post was written ?