Comment 12 for bug 1956787

I think the conclusion here is that on a focal server, if you expect to server non-nfsv4 clients, you need to enable rpc-statd manually with systemctl, and we should document it in the server guide (https://ubuntu.com/server/docs/service-nfs).

Unless there is a trivial way to change this that for sure won't impact other scenarios, I'm wary of touching the systemd unit files in such a fashion on an LTS release, for fear of introducing other bugs or regressions, specially because this behavior was specifically introduced by a debian/ubuntu patch.

On the flip side, the reasons for the patch might no longer exist nowadays, so I think it's valid to revisit this for the upcoming LTS release, 22.04. In fact, quickly looking at the nfs-utils package in debian/experimental shows they apparently dropped this patch already:

nfs-utils (1:2.5.4-1~exp5) experimental; urgency=medium
...
  * Drop "Let sysadmins enable/disable statd services"
...
 -- Salvatore Bonaccorso <email address hidden> Tue, 14 Sep 2021 09:48:58 +0200

So that's my plan:
- document that rpc-statd might have to be manually enabled (note that even a focal nfs client will default to nfsv4.2, not requiring statd on the server nor the client)
- close this bug for focal
- see what we can do for jammy (22.04)