Dropped Wifi calls in my mesh network - strong signal and using pods

I am having issues with dropped calls while using the mesh Wifi network in my home. 

I have a Comcast modem and three Comcast pods.  Two pods are downstairs at opposite ends of the house.  One pod and the base station (or modem) are upstairs at opposite ends of the house.  When moving upstairs to a location between the upstairs pod and the base station, my Wifi calls almost always drop.  In late August, a service technician came out to my house to take a look at this; upon my description of the problem, he checked the signal going into my house and installed both a new splitter and filter upstream of the modem.  He added he wanted to check the quality of the signal coming out of the coaxial cable going into the modem and added that a bad signal due to cable problems could be causing the modem to create dropped calls at this one location in my house.   Due to someone sleeping in the room where the modem is at the time he was at my house, I was unable to let him check that signal.  He did provide three debugging steps for me: 

1) Using each of AirPort utility and the signal strength indicator on the phone, check to see if there is a dead spot where there is no signal in my network.  I tried this and noticed the signal strength near the pods was around -30 dBm and away from the pods was around -65 to -70 dBm.  No place near where I was getting dropped calls did it go much lower than that.  I also noticed that the signal strength never dropped below 2 bars anywhere in the house.  

2) Replace the modem with a new modem.  The service technician gave me a new modem of the same type and I installed it.  The results were no different than with the first modem except now the signal strength near the pods is -15 to -20 dBm and around -40 dBm elsewhere.  

3) Put another one of my iPhones on Wifi calling and see if calls drop in the same location; I tried this and the calls drop in precisely the same location.

On September 10, while speaking with Comcast technical support, they suggested the problem may lie with the phone not being able to handle a handoff between the mesh network of the pods and the modem base station.  Given the location where the dropped calls are occurring, this made sense.  The rep said the way to fix this was to disable bridge mode on the modem, as this would disable the modem from being able to handle cell calls and all cell calls would go through the pods.  I have since disabled bridge mode on the modem (went to 10.0.0.1, and ensured the red part of the bar said 'disabled'), but this did not fix the problem.   Considering the location of the dropped calls, I am more inclined to believe the tech support rep who said it is likely an issue with the phone not being able to handle a handoff between the mesh netwjork of the pods and the modem base station.  But he seems to be incorrect that disabling bridge mode will force the phone to conduct Wifi calls strictly through the pods.

Modem details:

New modem: TG02DCW3482P2CT

Old modem: TG02DCW3482P2CT

Pods: Xfinity X3