So, what side effect of NAT is making your server unreachable here? It sounds like you could turn the NAT off and it would be exactly as unreachable as it was when the NAT was on.

(Just to double-check... have you tried DHCPv6-PD? ISPs will normally only give your router a single IP on its WAN interface, or sometimes no IP on the WAN. Getting the routed prefix for the LAN-side networks involves doing a PD request, which is separate from requesting the WAN IP.)

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Spivak 2 hours ago | parent [-]

With NAT your device does not have a publicly routable address. Attackers have no way of contacting you at all. Without NAT you have a publicly routable address and attackers can try reaching out to your device. You rely entirely on your device's and your router's firewall.

So it's not really about NAT although it ends up being a consequence—it's about having a truly private network "air gapped" from the public internet.

	▲	Dagger2 an hour ago \| parent [-]
		No, NAT only affects which IP your connections appear to be coming from. It doesn't change which IPs your devices actually have. The person I replied to said that they only get a single v6 address. If that's true, it doesn't matter whether they have NAT or not; their network isn't going to have publicly-routable addresses either way. If your network is air-gapped then no connections will be happening at all, in or out... and if you connect a router to both the Internet and to your network, and enable routing on it, then it's not air-gapped any more.