Apple TV and XFi

We’ve had Comcast bundle for 4 years. We’ve never had any major issues rebooting didn’t fix. We recently installed Apple TV and few days later, one by one, other devices Can connect but unable to download anything. Desktop iPhone Xbox. It seemed to be selective in which devices around the house can connect (Alexa smart tv, phone line...) Called Comcast And the usual on and off plug unplug process. we switched our plan to unlimited and recently got a newer version if router/modem from Comcast. It solved the issue for awhile then started dropping connection Again with even more devices affected. I uninstalled Apple TV and forget device in my xfi app to no avail. Anyone has same issues?