You're talking about using NPTv6 with ULA's. Remember, IPv6 is explicitly designed to allow having multiple addresses on an interface - you can have a ULA for i

You're talking about using NPTv6 with ULA's. Remember, IPv6 is explicitly designed to allow having multiple addresses on an interface - you can have a ULA for internal connectivity and a GUA for everything else. This is the situation I settled on for my home, because having redundant ISPs means a lot of headaches and I obviously do not qualify for a PI allocation. Every machine on the network gets a ULA address that remains stable, and to deal with ISP failover I have a script on my Mikrotik router to change advertised prefixes when the primary ISP goes down. Took more work than my v4 NAT setup, and I hope more network vendors build-in support for the WAN failover bit in particular because every consumer/prosumer kit I've used does absolutely nothing for v6 traffic (I literally could not have done it without Mikrotik scripting or rolling my own router because no off-the-shelf distro like opnsense/m0n0wall/etc have support for this).