Can only access ipv6 sites on xfinity with cm1150v

[robotelbow]

I recently subscribed to xfinity and haven't been able to effectively use it since I signed up around a month ago. No matter what I try, I can't seem to access any ipv4 sites. I can't ping any public ipv4 ip addresses so I don't believe it's a dns issue. Plus, I can actually resolve the hostnames to an ipv4 address; I just can't access them. I googled around and some people with other models of modems had similar issues and they got it to work after a factory reset. I've done those a ton of times and it doesn't make any difference. I've also tried resetting it with the coax cable unplugged because one guy said that worked for him but no such luck for me. Comcast's tech support isn't very helpful and as near as I can figure, if a factory reset doesn't fix it then they don't want to know about you.

I can ping the modem's ip (192.168.100.1) and I can access other devices on my local 192.168.100.x network, but unless it is ipv6, I just can't access anything on the internet from any of my clients - even when connected directly to the modem. If anyone has any insights, I'd be really really grateful.

[FURRYe38]

Do you have a router between the CM modem and your PC or is the PC directly connected to the CM modem? 

[plemans]

I'd read through this thread. If you google xfinity ipv4 sites not working, there's a bunch of issues and they tend to be on xfinity's end.

https://forums.xfinity.com/t5/Your-Home-Network/Can-only-access-some-sites-IPV4-IPV6-megathread/td-p...

[robotelbow]

I have tried it both ways. In the case where I have a laptop directly connected, I give it a static IP since the CM modem doesn't provide dhcp or anything, and then I set the laptop's gateway to 192.168.100.1 - the modem's ip. It has the same behavior as when there's a router, that is, I can not access ipv4 sites on the internet.