How to handle ISP IPV6 prefix delegation change ?

[Truxi]

Hello,

I'm still configuring my IPV6 for home network and I have solved what I thought my last issue with this post: https://forum.opnsense.org/index.php?topic=43885.msg219037#msg219037.

I have now a private static IP for routing my local IPV6 devices to my DNS service and ISP can change my delegation range, it's not an issue anymore (for this).

Except that I observe now firewall issues (that were here before, I just didn't noticed it) when I reboot my ISP router as it assigns me a new delegation prefix.

I'm not sure if it's exactly the issue but when my ISP router reboot, I get my new prefix, DHCPv6 start issuing new  IPs for this range but old device are still on the "old" IPV6 prefix, so it doesn't match current networking state of OPNsense this I can observe a lot of "Default deny / state violation rule" coming from "old" prefix IPV6.

What is weird is that some devices won't renew, even by rebooting, so I'm a bit lost now on how to deal with this situation, would like to know if some of you are in the same situation and how you handle it 

On my setup:
- ISP providing /56 and delegating /64
- WAN in DHCPv6
- LAN Track WAN
- Router Advertisements Assisted