Looking at your account, it seems like you own your own modem, the TG862G. I'd probably recommend doing a hard reset on it and re-configuring it.
It's pretty old and it may be worth considering upgrading. Seeing as how your service includes Voice, you can look into the following models listed on https://www.xfinity.com/support/devices/:
Two options listed there include:
There are others but they are also dated.
How does one own a TG862 ??? That's a Comcast supplied only device. It's not a retail device ..... How did it ever get provisioned for service ?
I believe it is a Retail product. Bought it at Best Buy so I could own it and not pay the monthly charge to Comcast. Its probably 2-3 years old. Tried rebooting it by disconnecting the power supply but no help. Maybe I just need a new modem.
AFAIK, the TG862 is a rental only device. They are not supposed to be able to provision them for service as they are typically listed in their database as being unreturned / stolen.
@EG Good question, sounds legit based on comments below. Anyhow the device is old regardless and the replacement is the right path. @fmcllc if you're keeping Voice services just make sure you purchase a modem that supports it.
I always advise posers to never buy used modems on sites like e-Bay or Craigs List for the reason I stated earlier.
FWIW, one should be careful if buying used modems on sites like eBay. Many times they wind up being listed in Comcast's database as having been stolen / unreturned and they won't provision them for service. To be safe, buy only brand new modems in their original packaging from reputable retailers.