On Tue, 28 Mar 2023, Andy Smith wrote:
Thirdly, if no special handling is in use then your operating system chooses which address to use. There's an RFC for that, and all of that is configured in /etc/gai.conf on Debian. The default behaviour is to try IPv6 first.
The default differs from RFC 3484 See the comment in gai.conf If you are using ULA then ipv4 will be chosen in preference.
I have configured an ipv6 tunnel.
The op doesn't say how this is configured but ULAs often appear around tunnels. uncomment the first five lines here to do what RFC3484 suggests. #label ::1/128 0 #label ::/0 1 #label 2002::/16 2 #label ::/96 3 #label ::ffff:0:0/96 4 #label fec0::/10 5 #label fc00::/7 6 #label 2001:0::/32 7 Tim
