My wifi keeps cutting out non stop.

 For 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. 

Hi @user_14664c, Welcome to Xfinity. I'm sorry to hear about your connection. Did you install your services or did a tech come out? 

Have you checked all your connections to ensure everything from your modem to the wall outlet is finger tight and secure?  Are you renting our modem or do you own?

I also have a link for troubleshooting steps from our help and support site at https://www.xfinity.com/support/internet#troubleshooting/your-connection. 

@user_14664c 

Have you had a chance to try that test ?