PSA: recent Comcast firmware seems to break prefix delegation for static IPv6

[really_lost]

I lost my IPv6 prefix delegation about a week ago. Seriously dug into it yesterday and have packet captures of the modem telling me no prefix delegation.

For anyone else using anything besides the base /64 of your IPv6 statics, don't waste much time on this. There's a forum thread on the Comcast support that makes it clear this is an issue with the latest firmware. It even includes someone who got their modem swapped out. The swapped out modem came with older firmware. Prefix delegation worked again. A few days later, the new modem switched to the latest firmware and prefix delegation broke.

https://forums.businesshelp.comcast.com/conversations/ipv6/prefix-delegation-disabled/690fa973a2c50219bf21c6e6

It's pretty clear that firmware CGA4332COM_8.2p5s1_PROD_sey breaks prefix delegation for Comcast customers.