Peer-to-peer (P2P) connection issues?

[railswrack]

I play an online game that uses a P2P connection between players (One player hosts, and the other players feed off their connection). The connection strength between the host and the other players is indicated by connection bars like the reception bars on a cellphone (1 bar = worst, 5 bar = best).

When I first used OPNsense with all default settings, players who would typically have a 4 or 5 bar connection with me hosting were getting only 3 bars. Turns out this had something to do with my NAT.

So I changed my gaming pc's ip to static, switched my NAT outbound mode from automatic to hybrid, and added this rule.

This solved the issue until now. Yesterday my ISP (Xfinity) had a maintenance, and now I'm having connection issues with specific people. For example, my friend who lives like an hour away from me who usually has 5 bar connection with my hosting is now only getting 1 to 2 bars. He has ATT&T as his ISP. While other people in the same party who live way farther away from me are still getting 4 bars.

Similarly, when my friend hosts, I'm only getting 1 to 2 bars while other people are getting 4 or 5 bars. So, it's definitely something between my internet and his, I just have no idea what.

This only started happening after my ISP's maintenance.

I've tried restarting all my equipment. I've also tried installing the upnp plug in on OPNsense and adding my gaming pc's ip as an entry seen here.
Still nothing. I'm not sure what else to do. Is there something wrong with my settings? Should I contact my ISP? Thank you!