I've configured a domain controller in an Ubuntu Server 14.04 with samba 4.3.8 and although no errors during the configuration process, Windows clients can join the domain. A message "Network resource is not available" were shown.
Repeating the configuration with Samba 4.1.6 allow clients joining the domain without problems.
We need more details. Which Windows versions are you using?
Can you upload a level 10 log together this a capture?
we need traffic on all ports.
Does "allow dcerpc auth level connect = yes" fix the problem?
Finally, I could join Windows clients with samba 4.3.8 in Ubuntu 14.04 LTS. I had to install winbind and libnss-windbind.
Closing per comment #2 as a packaging issue.