I have some Windows nodes and some Linux nodes for a couple of different coins all behind my domestic broadband.

My Windows nodes have full Qt wallets, my Linux nodes are running headless daemons.

My Windows nodes are making IPv6 connections and show their own ip as an IPv6 address, whereas the Linux nodes do not connect with IPv6 and only show their own ip as an IPv4 address.

The Linux nodes are on Raspian Jessie Lite, when I do ifconfig the adapters have IPv6 addresses. /etc/modules has ipv6 in the file.

What do I need to do to get the Linux nodes listening on IPv6 please?

EDIT: As a test I added the internal IPv6 address of my Windows wallet to the Linux as an addnode=. The Windows getpeerinfo shows the Linux machine as an ncoming connection, but with its LAN IPv4 address...