IPv6 support

[JuniperChris929]

IPv6 support

[Chapoly1305]

This is not an direct issue of this project.
Firstly, access http://[::1]:3000/ and see if you can assess this from your host, I tested without any issue. Ensure you have allowed ufw or iptables to expose port 3000 to network. Especially if you are in a managed network like in company or school, double check if IT has not block the port by default.

If you are sure there is nothing wrong about the firewall, then there are two possible methods,

1. Use of Nginx or other software as a gateway, when user access a certain port of the host listened by Nginx, it proxy the request to your service, in this case, port 3000. This might be much easier if know Nginx.
2. Enable the IPv6 support of the Docker by referring https://docs.docker.com/config/daemon/ipv6/