Anyone experiencing wi-fi calling issues since IOS 16?

Wi-fi calling has been terrible for me (14 pro) and my Mrs (11 pro) since updating to IOS 16. We've got very poor cellular coverage at home, hence why we have to use it. The connection is so bad people say we're breaking up or can't hear us at all. We use Virgin media with their latest router, the Hub 5 and the internet/wifi connection is very good all the time. WhatsApp or Facebook messenger calls are unaffected. I almost ended my ISP contract over this, they keep saying there's nothing wrong on their end, and fair enough, the internet itself is flawless.

The only way I could improve this issue was by disabling the router's firewall. I don't want to be without the firewall of course. I think Apple changed something in IOS 16 and created an incompatibility with the pfSense.

Anyone else experiencing this?