Internet won't work properly. Not everything connect/loads

Internet isn't working correctly. I've done all the troubleshooting. I got a new modem. I tried using the AI chat, no help. I talked to an agent over the phone, they set up an appointment, acknowledging the problem is with Xfinity and not me, the appointment got canceled. It's impossible for me to talk with a real person and it's extremely frustrating. Here's the problem:

I can't connect any of my PS5s to the internet via ethernet cable. I can connect the PS5s via Wi-Fi, but when I try using a cable I get a message on the PS5 that says "your internet service provider or your router might be preventing your PS5 from connecting to the internet." I've tried using a different DNS, I've tried to port forward. It doesn't make a difference. I know the ethernet cable isn't faulty because I can use that same cable on my computer and it works. The PS5 can obtain the IP address but it fails to get an internet connection. It's been almost a week with this problem. I have never had any problems in the past and I've had the same PS5 since December 2020. Keep in mind that is this happening to two PS5s. I also tried to connect my PS3 via ethernet and it won't connect. 

Another problem is that some websites and some apps won't load over Wi-Fi. Even some Xfinity websites. When I switch over to mobile data there are no problems. 

My guess is that for some reason Xfinity is blocking some of my connections and there's nothing that I can do about it. I appreciate any help, I've tried everything that I can think of. Thanks.