said by NetFixer:
It would seem to me to be a Comcast issue when the router does support multiple IPv6 networks (I previously tested with my guest network behind it), and it used to get the /60 allocation but now it does not get it.
Comcast definitely used to supply the requested /60, but that suddenly stopped, and that is illustrated in the screen shots I previously posted. It is perhaps a total coincidence, but it happened after /60 vs /64 allocations were initially discussed in this forum in which I posted that I was getting a /60 assignment.
I PMed you my work email, send me your info like the DUID of your router and cable modem MAC..
But we are accepting anything up to a /60 via DHCP, but the route injection will not work on some CMTS's. I have tested this and I am using it so I know this works and doesn't work in some cases.
My config looks like this:
on My WAN
ipv6 dhcp client pd hint ::/61
ipv6 dhcp client pd prefix-from-Comcast
On my LAN's
ipv6 address prefix-from-Comcast ::1/64
ipv6 address prefix-from-Comcast ::1:0:0:0:1/64
ipv6 address prefix-from-Comcast ::2:0:0:0:1/64
and so on...