For some time I have a CX11 instance running at Hetzner. It is connected via vpn to my internal network. There was only IPv4 traffic sent over that connection and everything was fine. Until an idea occured to me: Why not use IPv6 over that tunnel as well? I mean, I did that on others servers, so why not on this one? Copy and paste of some lines of configuration and voila, I could “ping6” from the vpn server to the client. That was easy …
But suddenly my nagios went red because the external IPv6 connection was gone. Did I do some routing wrong? Stopping openvpn and everything was fine again. So I deactivated IPv6 and wondered why this tiny little server behaves different from any other.
After some time I found this article and I can confirm that Hetzner was not able to fix their bug after about two years of reporting it. Well done Hetzner!