I'm using StarLink as the ISP for a remote site I manage. StarLink doesn't supply static address for any kind of a "reasonable" price but they do provide a "reasonably stable" IPv6 /64 address. I have the StarLink router in bypass mode and am using a GL.iNet GL-MT6000 (Flint 2) router running the most current version of OpenWRT (24.10.4.x).
I have a simple server set up on the LAN side (RPi 5) that I've configured to "self assign" it's address via it's MAC address (I know, not the safest). So, that server ends up with something like "2605:cccc:aaaa:6666:da3a:ddff:fe31:0aaa" where the last four groups are stable. I use the NoIP service running their Dynamic Update Client (aka DUC) in IPv6 mode to keep the mapping of the URL name (like MySpecial.WebServer.org) to the IPv6 global address.
The issue is that whenever StarLink feels like pushing an update in their system the /64 prefix can change. The server then picks up the new prefix address and DUC see that address and updates the URL/address mapping. Then, the Traffic Rule in LuCI fails to forward traffic to the server.
I can use Port forwarding by that isn't really the idea with IPv6 management so I want a clean Traffic Rule for IPv6 that masks out the 64 bit prefix, matches on the 64 bit suffix, and forwards the request to the server.
I saw a very good YouTube by OneMarcFifty that implies I can just add a rule using the following mask and things should work:
/::ffff:ffff:ffff:ffff
But, before I drive all the way to that particular remote site and start messing with the firewall rule I'm hoping someone with better knowledge of OpenWRT can confirm the above. When I ask ChatGPT "it" doesn't have a very solid answer, and often times I've found that the dang AI tools are just giving me a "best guess" or otherwise making up stuff based on a lot of assumptions. I'd rather trust feedback from a HUMAN!