If you use Active Directory authentication and your LDAPS server returns "Can't contact LDAP server" error message, here is what you can try.
- On the machine where your web server is located create this file: c:\openldap\sysconf\ldap.conf
This name is hardcoded in PHP LDAP extension and can not be changed. Add this line to the file:
TLS_REQCERT never
- Restart the webserver
That should help.