You appear to be using an Active Directory. In this case, you still want to use port 389 for LDAP and 636 for LDAPS unless there is a firewall in the way or the ports were changed on the Active Directory for some reason. That said, it is possible that SSL was not set up for your Active Directory and therefore it is not listening for LDAPS requests on port 636. Make sure that LDAPS is enabled on your Active Directory. ... View more