Wifi

The concern is not "Home Security Devices And Equipment" help related........... Topic moved here to the proper help section for assistance. 

First. Check their site for official info on any possible local outages here;

https://www.xfinity.com/support/status 

Use a cell phone internet service, a public WiFi hotspot, or a neighbor's internet if you need to in order to check it.

Or you can use their Xfinity App: https://www.xfinity.com/apps 

Is / are the light / lights on the modem lit steadily or are they blinking ?