[GTALUG] server question

[o1bigtenor]

Greetings

Can't find any somewhat current information (less than 2 years old) on
what kind of an address to use on a server where its only for use by
lan members - - - NOT for outside use.

What I'm finding is at best 5 or 6 years old and then there is the
stuff that's more like 10 or more years old. Debian has moved from
iptables to nftables as of the latest release of stable (Buster or 10)
and I haven't been able to find anything.

Suggestions?

TIA