Certain websites won't load for months now and cannot get issue resolve. ERR_CONNECTION_TIMED_OUT

For months we've been having issues with our internet. Really frustrated that we are paying so much for services that doesn't work.  We aren't able to access tons of website on pretty much all our devices. Our ring camera cannot connect, now our Alexa is no longer able to connect to our wifi. We've troubleshooted until it became tiresome, swapped out modems, had techs come out who swapped  the modem again and did some sort of restart/restore that he said would take up to 3 days that would fix the issue. Then we are told that it's all our devices and we should contact the manufacture of each of the devices. This is impossible as if I go over to our neighbor's house who also uses Xfinity we are able to connect and use their wifi with no issues at all. The strange thing is that one day we cannot access let's say www.reddit.com then two days later we are, the same with Gmail, banks, school websites, government websites, etc. While browsing through the forum I've notice others have experienced the same issue and @XfinityJohnN was able to resolve the issue for them. I'm not a technical person but had assistance from my daughter who said the following

"It seems that somehow the router is blocking you from accessing random websites. Having done multiple tracert via cmd prompt it is clear that the issue is not device based but with the network."  I've attached the images that she provided. Please I am asking anyone out there that can get this issue resolved to help me. It's been over 3 months and we are getting frustrated as we cannot use something that we continue to pay for.