@Toasterson I'd recommend taking a look at #pfSense / #OPNsense for that task.
I've done Tunneling #IPv6 on #IPv4only WAN networks and had to deal with #CGNAT - #IPv4 + IPv6 and having to implement #DualStack on #WAN-side.
#wan #dualstack #ipv4 #cgnat #ipv4only #IPv6 #opnsense #pfsense
Today I started to make a list of #ipv6 reachable #mastodon servers. It will feature both the ones which work and the ones that don't. So far, it looks pretty good! The list is also reachable from #ipv4only hosts. https://redmine.ungleich.ch/projects/ipv6/wiki/List_of_IPv6_reachable_Mastodon_Servers
Next step: looking for an #ipv4only mastodon instance and seeing how it behaves when talking to this server. This server *can* reach the IPv4 Internet via NAT64, however it cannot be reached *from* the IPv4 Internet. (in case you wonder why: because A >> B and there is no mapped IPv4 address for this server)