samba - Jul 2017 - RPC server is unavailable

Posted earlier "samba AD not working" and the problem still exists.

Samba 4.6.5 AD

When attempting to join the domain I get the message "The RPC server
is unavailable".

Basically this was a classicupgrade which went well - and it works
fine on the local test system. And locally on the test network I can
join the domain just fine. However when I move the system, either via
moving the whole container (LXC) or building a new container and
restoring samba from the backup (samba_backup) on the local system is
where the problem occurs.

Because the IP address and subnet Isize as well) changes I need to run
samba_dnsupdate which seems to work but then the RPC problem occurs.

Any ideas?

Thanks.

I eliminated any possible problems caused by the samba_dnsupdate and
did the classicupgrade directly on the remote system and still have
the same problem:
"The RPC server is unavailable"

Everything looks right all tests in the wiki pass, the ports are open
and yet... systems cannot join the domain.