marrandy
Hello! That's unfortunate, I have some ideas:
The phone won't ring if there's no connection via wifi or cell. A vpn could possibly interfere since wifi calling would need dns resolution.
Your call history won't have a record while there's no connection or very weak/unstable.
Spam/blocked filtering maybe.
settings > system > reset > reset mobile
Switch off then on WiFi calling, VoLTE, Vo5G
Doubt this would affect anything but:
Your phone call app > unrestricted battery usage.
Try to not change settings in developer options
settings > system > developer options very top is toggle for "off" (if you don't see developer options, good)
Don't remove permissions or disable system apps.
Contact your carrier about any issues. Double check the APN settings with your carrier. (Under sim settings)
Get a new sim card.