I recently signed up with Xfinity and have a new modem. Ever since Xfinitiy service started, I get "your connection is not private" with a note "NET::ERR_CERT_COMMON_NAME_INVALID" on a number of websites. It further says "This server could not prove that it is ***.com/org/etc; its security certificate is from register.be.xfinity.com. This may be caused by a misconfiguration or an attacker intercepting your connection".When I click proceed to the particular site anyway, it takes me to modem activation page. When I go through modem activation again, it does not solve the problem. I can sometimes see those websites that seem to have been blocked on random occasions and I can certainly see those websites when I am elsewhere like a public wifi. I didn't have a problem with Spectrum. I initially thought this could be a chrome problem but it also happens with microsoft browser. I talked to a comcast tech and he says it is a modem issue. But I don't think it's a modem issue since I am connected to internet otherwise. Is there anyone out there who can help solve this problem?
I had xfinity on the phone yesterday and we got disconnected right after I went through the registration process successfully for the 5th time. Still having the problem.
My current workaround: when I get the intermittent error, I copy the url into a different browser and it works fine. I switch between Chrome & Edge. I also noticed, when switching back to the browser with the error after an extended period the page loads fine. For some reason instead of using the site's Certificate Authority to validate a secure connection it is using register.be.xfinity.com (which says the certificate is invalid).
Yes, I replaced the old xfinity modem with a new one. I just spent a couple hours chatting w/ xfinity and I am awaiting a call back. The tech I chatted with blamed it on my setup (which has not changed in 3 years). My xfinity modem is configured with 10.0.0.1 subnet. I have a netgear modem hardwired into one of the ports and is configured with 192.168.2.1 subnet. I use the 10.0.0.1 range for TV's and Sonos - mostly wifi. I use the 192.168.2.1 for computers and network storage. Again, this setup has been working for at least 3 years without any issue. What I find peculiar is that like the original poster, when I get the error, and check the SSL cert, it is wrong - rather than being the cert for the website, it is register.be.xfinity.com. Also, if the error page is left open for several minutes - the error goes away and the page loads!
My problems all started when I upgraded my internet modem. They merged my internet and voice services onto the new modem and my phone stopped working. My voice modem is in my basement.
A tech came out a week and a half ago and got that fixed but then my internet started acting up. I believe they did the reverse and messed up my internet.
I went out of town and couldn't deal with it until I got back. Finally got a tech out here yesterday and he swapped out my modem and supposedly fixed it. They had indeed moved my internet to the voice modem (also a new device). When they added the new internet modem they lost my old voice modem from their system.
But now things are flakey again.
I'm going to try replacing the coax and see if that helps but then I need to get in touch with support again.
How do you check the SSL cert?
Do you have internet and voice service? Do you have separate modems for each?
On a hunch, I unplugged my voice modem and so far I have not had any internet issues. Somehow it is conflicting with the internet modem. I have another tech appointment on Monday.