Can I Change Xfinity Cable Box WiFi Network to Google Mesh Network?

We have a three-story house with an X1 box plugged into ethernet on the 2nd floor. We have an extensive Google Mesh system expanding the Xfinity network such that it reaches every floor and every corner of every floor, basically runs all of our smart devices and our house. We rarely use our Xfinity cable because it seems so sluggish compared to our streaming services.

The Wi-Fi signals to all of our cable boxes except our main living room next to the router are very poor from the X1 box, but there are Google Mesh points RIGHT by them all. In the cable boxes under Device Settings / Network, there is no option to change the Wi-Fi network to the Google Mesh name. It's a fixed value set to the Xfinity network name.

That's obviously a problem since the Xfinity network signal doesn't reach the nooks and crannies of the house, and we have a bundle invested in the Google Mesh, have no desire to buy XFi Pods. The two networks (Xfinity and Google) can't have the same name or Sonos doesn't work properly, devices will jump back & forth between networks with the same name, causing issues.

SO, my question is, is there any way possible to change the network in Device Settings on each cable box such that it uses the Google Mesh network? If not, given the sluggish service, we'll have to reconsider having cable at all. 

Phone rep was not knowledgeable, kept trying to schedule someone to come out the day of my surgery even though I kept repeating that I would be having surgery.