Since I switched to xfinity internet, my browiser is getting hijacked
Since I switched to xfinity internet recently, my browser is now getting hijacked. I have been visiting a blog site for years without problem. Since switching to xfinity internet, the site is repeatedly being replaced with adds and popops for some sort of nonsense. It's the sort of hijack that you can't back out of, you have to close the browser entirely.
The ad pages even say "hello xfinity user!"
Why would changing ISP & wifi router open the door to this sort of hack?
windows 10 PC
Xfinity x1fi gateway