IPv6 configuration: /64 or /128?

[turicas]

In docs/pages/cloud/dedicated/network_ipv6/guide.en-ca.md it says every dedicated server gets a /64 IPv6 block, but on suggested Debian configuration it has net_mask 128.
I've checked my Debian servers (using OVH/Kimsufi's image) and my server IPv6 block is configured to /128 after a ip -6 addr list dev enp1s0.
The docs also does not use Debian's systemd configuration (systemd is the default init system on Debian since Jessie).
Between my servers inside OVH network I can ping the IPv6 addresses, but can't connect from outside using IPv6. What should I do?

[0xThiebaut]

I'd like to add that docs/pages/cloud/vps/configure-ipv6/guide.en-gb.md also states that the prefix (or netmask) of your IPv6 block usually is 128. This is incorrect, a prefix of 64 is needed otherwise the gateway is not part of your subnet and the routing won't take place!

/cc @OVH-Team-Guides @Fracasx

[xairoo]

Thanks @0xThiebaut! That bad documentation from @OVH-Team-Guides is so bad. How can we know the prefix? I wasted too much time.

https://help.ovhcloud.com/csm/en-vps-configuring-ipv6?id=kb_article_view&sysparm_article=KB0047575

The prefix (or netmask) of your IPv6 block, usually 128

Should be

The prefix (or netmask) of your IPv6 block, usually 128 or 64