pfSense

https://forum.netgate.com/topic/168410/ipv6-prefix-change-not-reflected-in-ra-messages:
"This may pre-date 20211210, which I upgraded to just before this, but I changed my LAN interface IPv6 address from xxxx:xxxx:xxxx::1/64 to xxxx:xxxx:xxxx:1::1/64 so as not to have the same prefix on LAN as my /48. After that, none of my machines picked-up the new prefix (for hours). Running tcpdump on one of them, the router was still advertising the old prefix (xxxx:xxxx:xxxx:0::/64, in effect).

The fix was to disable RA on the interface and re-enable it (unmanaged, as before). Prior to that, DHCPv6 (disabled) did show the new prefix, leading me to think I didn't need to worry about RA. Everyone came to life after RA started working."

RADVD should be restarted when changing the IPv6 address of the interface