Wifi Calling and Instant Messaging App Issues

I'm having consistent issues with Wifi calling and Microsoft Teams messaging since moving my home internet from Fios to Xfinity.  Incoming calls constantly go to voicemail and when making outbound calls I frequently get a "call failed".  Disconnecting phone from wifi and reconnecting seems to temporarily fix the issue but it always returns.

Microsoft Teams is the same.  Sometimes messages go through; other times they dont.

The same issues happen on my wife's phone (one is Verizon, one AT&T) so it is not a phone specific issue.  It has to be some sort of firewall setting on the modem, but nothing seems to help.  I have the firewall set to low security but still have same problems.  

Xfinity support has been completely useless so far.  Several chats with support that went nowhere.

Any ideas?