Let's say you get delegated prefix abcd::/64, and you distribute it in your LAN with DHCP. Now, every PPPoE authentication gets you a different prefix, so if y

Let's say you get delegated prefix abcd::/64, and you distribute it in your LAN with DHCP. Now, every PPPoE authentication gets you a different prefix, so if your PPPoE session gets dropped somehow, the clients in the LAN won't get the new IPv6 address until the next DHCP renewal. In this case, let's say the PPPoE session got dropped, and you got a new delegated prefix of dcba::/64. Your client's IP still has the abcd:: IP, while the router now only knows how to route the dcba:: prefix. The only way I found to make it work is to give clients a ULA prefix and NPT the ULA with the dynamic delegated prefix from my ISP.