It's not just NAT that's broken. On both Windows and Linux hosts, with bridged networking, SLAAC doesn't work for Linux or FreeBSD guest systems. It does even

It's not just NAT that's broken. On both Windows and Linux hosts, with bridged networking, SLAAC doesn't work for Linux or FreeBSD guest systems. It does eventually, after somewhere between 5 and 30 minutes, but for machines on the physical LAN it's virtually instantaneous. Something is dropping the router advertisements, but eventually one gets through. Once the guest has an address, it then works just fine. Not so great when all the systems you want to talk to are v6 only, and the v4 NAT address is just for legacy use.