I just ran the Comcast Connectivity Test (test-ipv6.comcast.net/index.html.en_US ). The message delivered was "No IPv6 detected. You appear to have no IPv6 at this time."
When I review the setup for IPv6 on my TP-Link AC1750 router, it shows a connection type of DHCPv6, an IPv6 address, a default gateway, and IPv6 DNS address.
Is IPv6 in use on my PC? Am I setup correctly? Why does the Comcast test disagree with the TP-Link setup?
Sounds like things are right ! That sometimes happens to me also with that CC test. Try this one and see what it says;
https://ipv6-test.com/ It should say 17 out of 20 if IPv6 is working correctly.
For a test, what does that test say with that computer connected directly to the cable modem (no router in the mix) ?
The IPv6-test.com reports IPv6 connectivity is "Not Supported". Score 4/20.
Is that with the computer connected directly to the modem (no router in the mix) ?
O/k without that test, it can't be isolated to being a Comcast issue, or your equipment.