[Samba] RPC server is unavailable

[Sonic]

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.