The behavior you describe violates RFC 4512 (section 5.1), while OpenLDAP complies with it. Please note that the root DSE is accessed using a plain, perfectly legal LDAP operation. The fact a client cannot be configured to perform such a simple operation clearly indicates the client is broken. A quick answer would be "get the client fixed".

<advertisement> I can imagine simple workarounds, consisting in few lines of code that allow to circumvent the issue. They probably require to hire some expert consultant. </advertisement>

p.