WiFi calling with AT&T Fiber Pace Router + Orbi : Caller can't hear me after ~10 secs

Hi FURRYe38 , this problem occurs even when I'm right next to the main Orbi router, so it's not an issue with my home size, interference, etc.     Remember that my iPhone thinks that WiFi calling works.   A WiFi call works as expected for about 10 secs, after which the person on the other end can't hear me but I can hear them.   At this point, the iPhone still thinks WiFi calling works because it continues to display "Sprint Wi-Fi".  So something happens after 10 seconds that cause the problem where the caller can't hear me.