Make sure that the hostname you use for your server is resolvable by DNS… something like “picturestravelsbooks” or “p” wouldn’t be resolvable unless it existed in /etc/hosts.
That’s another option though, you could always add each of those names into /etc/hosts.
This logic doesn’t make sense though. What do I do if the domain doesn’t exist (yet), OR if I don’t want to use FQDN ?
Many clients, even we, for instance uses names like NS1, NS2, etc to indicate nameservers and the FQDN makes a long name, which CloudMin then cuts off.