WiFi-calling doesn’t work with Verizon iPhone using Comcast WiFi

I switched my internet provider to Comcast. On that day wifi-calling stopped working on all 3 of our iPhones (which are all different ages and types). I have spent hours trying to figure this out with Comcast and Verizon. Neither have a solution. WiFi-calling has worked for all 3 of our phones for years until the day I switched my internet provider to comcast. All my settings are correct. Any ideas out there? Would be grateful. Thanks.