With IPv4 addresses nearly exhausted everywhere the world could really use some more IPv6 adoption so here’s a handy guide for getting IPv6 to work on your OVH Ubuntu VPS’s, although this guide should work equally well on any VPS/Dedicated server host.
At the time of writing this there seems to be a bug in netplan which stops IPv6 working properly when using the official instructions from OVH, this can be fixed by bypassing netplan and doing the configuration straight from systemd-networkd
Open a new file
Edit in the required config lines, making sure that you name your network interface correctly.
After you’ve written out the configuration you have two choices for making sure the changes are applied
Gateway=Your IPv6 Gateway Address Here
Address=Your IPv6 Address Here/128
Destination=Your IPv6 Gateway Address Here
Either reboot your server entirely
Or restart the systemd network daemon to apply the change, this is faster of course, but may cause networking to drop for a few seconds.
systemctl restart systemd-networkd