I recently moved my MainWP Dashboard to a server from Hetzner. Their servers automatically have IPv6 enabled.
I noticed that three websites from my 110+ websites were not reachable. They are all located at the same host (MijnDomein). When I try to open the site directly from the command line of the server, I also cannot reach them. Their IP is 34.240.216.169.
I tried to reach these websites from a Digital Ocean server which also has IPv6 enabled. Same problem there. So this seems to be a IPv6 issue, and not an issue that is provider related.
I set IPv4 as preferred on the server at Hetzner, but that didn’t solve the issue.
In short:
Websites from this specific host are reachable from server without IPv6 address and functionality
Websites from this specific host are not reachable from servers with IPv6 address, tested at different providers
Has anyone ever seen this before? I know a bit about working with servers and connections, but my knowledge is extensive enough to solve this issue…
Maybe the whole IPv6 thing is just a coincidence. It could also be an IP block in the firewall, so contact support on both sites to verify that the other IP addresses (v4 an v6) aren’t blocked by them.
That was my first thought. However, I tried to connect to the websites from two different servers, at different providers (Hetzner and Digital Ocean) at different locations (Nurnberg and Amsterdam).
MIjnDomein claims that they’re not blocking the traffic…
Can you try reaching those three websites from a host that is verifiably using IPv4?
If the sites aren’t reachable with IPv4 either, then it may be a good idea to contact MIjnDomein again and present them with that information.
If they are reachable, then the issue indeed seems to be IPv6 related. In that case, it may be a good idea to contact either Hetzner or Digital Ocean, and have them investigate why the connection may be failing when IPv6 is used.