TV Apps Keep Dropping

I just wrote up a very descriptive post to help explain everything and of course the Xfinity site failed before I could save. So I will have to add a less concise description here. Hopefully there are enough details below. 

We have 3 Xfinity Wifi boxes and we talk into the tv clicker to have apps pull up. We have people watching different things at the same time. Aka one room will have Netflix on and another is watching Hulu. Both using the comcast box for the apps. Quite a few times throughout the day the app will just fail. All at the same time. However, the screen goes black for a few seconds and right back to the cable tv. It could be the internet, but wouldn't the cable tv not work at the same time where that is wifi run as well? This has been happening for maybe the last 1-1.5 months. 

I have tried the general fix steps that you get every time when calling Comcast. Same with wifi reset.

Info to help: I finally got rid of that horrible and unstable Xfinity Modem/Router. Arounds 6 months ago, I had purchased a Surfboard G54 and 2 TP-Link BE19000 Routers. I setup the Surboard, put in bridge mode to shut down the wifi capability, and did a Mesh Network with the 2 TP-Links. Anywhere you go in the house we will run between 1.5-2.3 gbps...even over wifi. We had a tech come in when I bought them to check the cable stability and it was all good. I will say that when I first tried to setup the new network it was a nightmare. It turned out that the Surfoard was not sending an IP address to the router. I got it to work but when I had to restart the network it would be a nightmare again. I selected an option that helped with the IP issue but don't recall what it was. I know the IP issue is a Comcast problem and would love some help on that as well. I want to find a way for the router to easily pick up and get sent an IP. 

Since the change, we can go anywhere in the house and the system will switch out electronics seamlessly to the best signal. We also have finally gotten stability with the internet. This new issue has been frustrating, and I appreciate any help you can give! Thank you