By any chance do you have client isolation or network isolation enabled in Wifi or Untrusted network set in PC firewall ?
For instance I would expect that behavior on my guest Wifi.
I frequently see notices about blocked traffic in my router logs due to attempts to communicate with Private IP addresses e.g. some other players local LAN address instead of their public WAN address. It makes me think WF first attempts to have clients communicate via local LAN address before resorting to the forwarded WAN ports.
That matters because many routers do not support "hairpin" routing e.g. you can not communicate with your own public IP.
By any chance do you have client isolation or network isolation enabled in Wifi or Untrusted network set in PC firewall ? For instance I would expect that behavior on my guest Wifi. I frequently see notices about blocked traffic in my router logs due to attempts to communicate with Private IP addresses e.g. some other players local LAN address instead of their public WAN address. It makes me think WF first attempts to have clients communicate via local LAN address before resorting to the forwarded WAN ports. That matters because many routers do not support "hairpin" routing e.g. you can not communicate with your own public IP.