Dropped WiFi calls on iPhone X iOS 12 ATT with Orbi RBR50

checked the items you suggested.  

* The ISP WiFi is disabled, I only enabled it to test to see if calls would drop if my iPHone was connected to the ISP WiFi and the calls do not drop on ISP WiFi.  This is why I think the issue is some sort of compatablity between iOS 12 and Orbi since my WiFi calls do work fine on other WiFi systems only have issue on Orbi.  

I'm using WPA2-PSK (AES)

I have about 20 WiFi neighbors around me, although since WiFi calls work from the ISP WiFi and the 20 WiFi neighbors have been around for the past year I think that can be ruled out unless there is a specific setting in Orbi that might need to be enabled for this many WiFi systems around me.  

I set channel to manual on 2.4ghz and changed the channel on 5ghz.  

IPv6, MIMO, daisy chain and fast roaming are disabled.  MIMO was enabled and I disabled it all the others were already disabled. 

I do think it is an iOS 12 with Orbi issue since iOS 12 WiFi calls work on other WiFi systems and it was working with Orbi prior to iOS 12.  I lean toward some setting tweak needed in Orbi and I have tried so many with no luck.