some website can not access

I've this problem with my current modem. If I connect to sites such as 'https://home.getvera.com' or 'spotify.com' or 'Xfinity.com' I get "cannot reach host..." error page on my Windows Edge browser. I've talked to customer support at least once and temporarily it seemed like whatever magic was done on the support side resolved it. a prolonged power outage resulted in the return of the issue, only a couple of sites deep there's a user for the Xfinity (residential internet) forum that had this problem (with a more thorough approach) which a user noted (not the original poster was fixed by changing the name of the 2.4G and 5G networks). I'm trying this at my business today to see if this conflict exists