Inconsistent Internet - Linksys Mesh System

Since working from home I have noticed how poor the Wifi coverage in my house is with just the Xfi Gateway.  With all of my kids at home as well, where I sit for my 'office' is a good distance away from the Gateway. The Gateway is on the 1st floor far left corner, and I sit on the 2nd floor far right corner of my house.

I initially purchased the Xfi Pods (3) and placed those in various places in the house to try and improve the Wifi coverage.  I finally gave up and decided that this would not work out.  I then purchased a Linksys Tri-Bank VELOP Mesh Network system.  This seems to work much better than the pods, but I still have very inconsistent Wifi coverage.  Depending on the day, my Wifi coverage drops at least once, but sometimes every 15-20 minutes for several hours.  This occurs at all times of the day and night, not just peak hours.

Every time I look at my Xfi app it says that the signal coming to the Gateway is strong, seems to never waiver which I find to be suspect.  I did not put the Gateway in Bridge mode because I was told that wasn't necessary.  Some of my devices, like Ring doorbell, etc are still connected directly to the Xfinity Wifi, while most devices are connected to the Linksys Wifi.  If I switch the Gateway into Bridge mode, would that do anything to improve the Linksys system?  

Is there anything else that I can try to make the Xfinity system more stable?