I've installed Ubuntu 22.04 on a machine and I am trying to mount an NFS share which has no problems mounting on an array of other Linux Ubuntu machines.
I'm having a number of troubles setting up an NFS mount on a Ubuntu server, and the main issue seems to be in making connection from the client (a Mac).
showmount works by contacting the server's MNT service directly. NFSv4-only servers have no need to advertise their exported root filehandles via this method.