Internet constantly dropping

Is this with a WiFi connection ? If so, as a test, does a computer / device that is hardwired directly to the router / gateway device with an ethernet cable have the same problem ?

With this test, we are trying to isolate this down to being either a WiFi-only problem or a problem with the general connection to the Comcast system which would of course affect both. It's a good first step in troubleshooting before proceeding any further. 

Some tips for improving WiFi performance;

http://corporate.comcast.com/comcast-voices/10-ways-you-might-be-killing-your-home-wi-fi-signal 

https://forums.xfinity.com/conversations/internet/answered-how-to-improve-your-xfinity-wifi/602da486c5375f08cd804f16 

https://www.xfinity.com/support/articles/internet-connectivity-troubleshooting?linkId=180985598 

There are other options. Google for WiFi repeaters / range extenders, WiFi mesh systems / pods, powerline ethernet adapters, MoCA adapters. Good luck !

https://www.cnet.com/how-to/your-router-isnt-as-fast-as-you-think-it-is-heres-why/  

https://www.cnet.com/how-to/home-networking-explained-part-2-optimizing-your-wi-fi-network/ 

https://www.smallnetbuilder.com/wireless/wireless-features/wi-fi-ping-spikes-causes-and-fixes/ 

I guess my question is why does it show strong performance on the Xfinity app but constantly disconnecting or ‘pausing’ on the devices’ end? It’s a brand new gateway!