[Samba] Cannot join Windows XP Pro to new Samba 4 AD

[dahopkins at comcast.net]

I have upgraded my Samba3+LDAP system to Samba 4 following the instructions given here: https://wiki.samba.org/index.php/Samba4/samba-tool/domain/classicupgrade/HOWTO 

I did this on a test server (so I also moved the ldap database, installed openldap, etc). 

The installation passes all the simple tests suggested here: https://wiki.samba.org/index.php/Samba_AD_DC_HOWTO#Testing_connectivity_to_your_Samba_AD_DC 

However, when I attempt to join a Windows XP Pro system to the domain, I get an RCP error. Also, if I attempt to log onto a system that was already joined, I am prompted for a password change and then I get a message about the domain not being available. 

Both of the Windows systems had the registry changes that were once required for Samba3 (signorseal in particular). 

I have not been able to find any information about the RPC error that makes sense. Some have suggested adding entries such as https://lists.samba.org/archive/samba/2013-January/171216.html 

If anyone has any suggestions for troubleshooting, I'd appreciate the advice. 

Sincerely, 
Dave Hopkins 
Newark Charter School