A couple of suggestions:

One: Use Data::Dumper to inspect what's in that hashref. Might be interesting (or informative).

Two: Coinciding with your server upgrade, did you upgrade your version of Net::LDAP, or one of its dependencies? If you're VC'ing your module stack you might be able to roll back to a previous stack of module versions, possibly to good effect.

Outside of that, I'm out of ideas. Hopefully now that your node has been edited so that it's somewhat legible someone with some experience with Net::LDAP can chime in.