IPv6 Git clone fails in discourse-setup, but works on the machine?!?

I’ve hit issues with Docker on IPv6 only systems in the past related to the lack of NAT, since Docker often uses IP addresses that are only accessible from the host but NAT is not automatically configured by Docker for IPv6.

This repo’s readme describes that problem more fully: GitHub - robbertkl/docker-ipv6nat: Extend Docker with IPv6 NAT, similar to IPv4 · GitHub