Is this a single static IPv6 address with a /64 (or /56 or /48) subnet routed to it? Or is it something else?
Thanks, Moisey Cofounder DigitalOcean
A sane setup should use a transfer net on your interface, and should route your actual address space to your gateway address on that transfer net - otherwise you'll need ugly hacks such as proxy-NDP in order to be able to route addresses for sub-allocations. This flat setup without a transfer net was invented for IPv4 when IPv4 addresses became scarce, so it was a necessary evil, but it's a stupid setup that causes nothing but pain when you have billions of /64s available.
That is the reason why I don't understand why anyone would even test with single-address allocations.
The implementation is important, over the years I've had annoying experiences with certain providers trying to do IPv6 - but not getting things quite right:
Hetzner - Gave customers a /64, but using additional IPv6 addresses required setting up proxy NDP - which at the time was annoying as only more recent Linux kernels supported it. I believe they've improved on this since though.
OVH - Requires setting up a default route outside of your normal netmask - this isn't fun. We don't do this with IPv4 - so why do some providers do it with IPv6?
Linode - Enables IPv6 auto-configuration, so many servers share the same /64 by default, and they give accounts "pools" of /116 allocations. Sites like Google considers all of them to be part of the same /64 network - so your server will probably have trouble accessing certain resources if another server is doing excessive queries.