I just found found your modem MAC from the trace you provided to @Datalink yesterday. Performing initial troubleshooting was showing your modem completely offline. If there is a tech working on your line, that explains this part.
Keep me posted.
A cable issue won't affect the IPV4 issue. If the cable issue was bad enough it would affect anything that is internet connected, but, your IPV6 works. If you can forward the MAC address to @RogersDave that would make this easier to check.
I think I see the problem but yes it will take some magic....
I'll get back to you later today on this one. Need to call a few favors 🙂
Run a speedtest at http://speedtest.xfinity.com/
That will run both IPV4 and IPV6 speedtests. See if you can get there via IPV6. If so, and it runs, but doesn't run the IPV4 test, that basically proves the issue is beyond the modem, which will take Dave and the engineering staff to resolve.
Swapping out the modem and seeing the same result, ie: IPV4 doesn't work will reinforce that statement. You will need to forward the new modem MAC address as well if you are going to keep that in place so that Dave can track down the modem.
Edit; For the speedtest, try the Detroit and/or Chicago servers.