Answered: How to make LDAP plugin work with Global Catalog?

This change to the ldap plugin made it work in LDAPServer.php:

-    $this->con = ldap_connect($ldap_host, qa_opt('ldap_login_port')) or die ("Could not connect to $ldap_host host.");

+    $this->con = ldap_connect($ldap_host.':'.qa_opt('ldap_login_port')) or die ("Could not connect to $ldap_host host.");

I found this in the comments section of PHP: ldap_connect - Manual.  The change is to pass one argument (host:port) instead of two (host, port).  Ideally, both methods should have worked.  Don't know why it isn't.  I'm happy this is working now and haven't dug further.