I recently got a new ISP (Comcast/Xfinity), and also purchased a brand new modem/router (Arris SB6782-AC). I am having an odd issue where I can only get onto some select websites. I can get on the Google family of sites, Google, Gmail, Youtube, etc., but cannot get on almost any other sites. I have a good connection, as it tests at about 28mbps down. The same problem is occurring if I go on WiFi or ethernet, and is occurring with all my devices. I have talked with Comcast tier 2 tech support, and they say everything is good on their end, and have re-provisioned my modem several times. They feel the issue is with the modem, however after 1+ hour on the phone with Arris, they think the issue is with Comcast. I have tried many different solutions, from trying different DNS configurations, to resets, to clearing network settings. I have also browsed many other forums, and lots of the solutions I see do not work for me. Any help would be much appreciated. Thanks!