My ISP is only ipv4. It doesn't matter if an OS technically support ipv6 or not.

You can get a Hurricane Electric free static v6 tunnel.

They have poor reputations and are blocked from streaming sites and so on. But when you're the server, that doesn't affect you.

Note that you need a static v4 and DMZ because the tunnel protocol is a very simple one - presumably because they run it on giant routers. It just puts a v4 header in front of the v6 header. No TCP or UDP.