said by theisonews:I have no router only modem and it's an Arris tm822 from the link you provided I get
Your CMTS is not supported at this time
Your IPv4 address on the public Internet appears to be
removed
Your IPv6 address on the public Internet appears to be 2002:328c:3f32::328c:3f32
Your IPv6 service appears to be: 6to4...
The statement "
Your CMTS is not supported at this time" means that your local Comcast infrastructure does not support native IPv4/IPv6 dual stack. That is why the Comcast IPv6 speed test does not run.
You do seem to have IPv6 connectivity using a 6to4 tunnel, but that means that Windows tries by default to use IPv4 connectivity before it tries to use IPv6 connectivity, and I believe that is the reason that Comcast's speed test does not even try to run the IPv6 test. While there is a way to force Windows to give a 6to4 tunnel priority over IPv4 traffic, I am not going to even point to any articles explaining how to do that since I don't think it is a good idea
(one of a small number of network default settings that MS and I agree on).