This is a product limitation.
LDAP SSL uses ports 3269 and 636 but IMSS Windows does not support LDAP SSL. The table shows the ports used by LDAP and LDAP SSL services/protocols:
Service Name | UDP | TCP |
---|---|---|
LDAP | None | 389 |
LDAP SSL | None | 636 |
Global Catalog LDAP | None | 3268 |
Global Catalog LDAP SSL | None | 3269 |
For more information about Active Directory and how it works, refer to the Microsoft article How Active Directory Searches Work.