[SOLVED]
Hi all, I finally managed to resolve it so posting it here for others.
I went through all the logs in folder /var/log/univention and noticed in particular that the log of listener.log had errors “( ERROR ) : start_tls: Can’t contact LDAP server” for connecting to the ldap server .
Since the server is being the firewall and even for it’s internal ldap service using FQDN, it was apparent that it is not using its own (or new IP).
The fix is that one need to edit /etc/hosts and change the IP address for the hostname to the new IP address.
In nutshell, while migrating, please make sure that the IP address for the hostname should be updated as well.
I managed to resolve it no