I started this guide because I wanted to use Volumio. Since IPv6 didn't really work and the paid version of Volumio was prohibitively expensive, I decided against using it.

Enabling IPv6

Using Volumio 3.051-2021-03-06 as an example, vim /etc/sysctl.conf

net.ipv6.conf.all.disable_ipv6 = 0
net.ipv6.conf.default.disable_ipv6 = 0
net.ipv6.conf.lo.disable_ipv6 = 0

After a reboot, the DHCPv6 daemon works immediately and you get an IPv6 address or stateless addressing, depending on how the local network is configured. However, even with this hack, IPv6 support isn't really functional.

Shairport Sync

Works without issues on IPv6

Samba

Works without issues on IPv6

dnsmasq

Works without issues on IPv6

sshd

Works without issues

Web Service

This uses a NAT rule that initially only works for IPv4. It's a poor solution anyway. ~~I recommend using an existing reverse proxy and directing requests to the IPv6 address of Volumio on port 3000. Alternatively you can install Apache or Nginx locally to handle this task. The internet is full of reverse proxy howtos. Once you've created an AAAA record for the host, you can also access the correct port directly, e.g.:~~~~http://myvolumio.network.com:3000~~ Unfortunately this doesn't work. Both direct access via IPv6 on port 3000 and going through a reverse proxy result in errors...