Periodic WiFi Internet Dropout

My wife and I both work at home and use Webex/Teams/Zoom throughout the day.  In addition we use a Streaming TV service (YouTube TV) typically in the evenings.  I also have wifi calling turned on my cell phone.

What I've noticed over the last month is that we get call drop outs.  We'll be on a Webex call and the call audio will stop and then the sound of reconnecting.  My wife uses VPN for her work and the VPN will drop and reconnect.  I've also noticed the same thing on my iPhone 6 Max.  A call audio will drop.  The person on the other end will be saying "Hello?  Hello?" and then it comes back on.  Finally, when we're streaming TV in the evenings, we've been getting constant buffering, irrespective of the channel.

This tells me that it's either WiFi (which I highly doubt), the Internet gateway device, or the Internet itself.

I have AT&T 45Mb Internet, with the AT&T U-verse Model 5268AC gateway device.  The WiFi on the unit is turned off as I'm using a Netgear Orbi RBR50 Mesh network (thus the reason I doubt it's the WiFi).  

I've checked logs on both the Orbi and the Gateway and only see some err codes in the Gateway.  But they don't seem to correlate to the time of the dropouts.  I called AT&T and they ran test, I ran tests myself on the Gateway and Orbi Router, and even used the Smart Home Manager to no avail.  Nothing shows any problems.

Anyone else seeing something like this or have any ideas?  Thanks!