by Iñaki Arenaza.
DN cn=admin.dn=mydomain,dn=edu
Is this a typographical error? The syntax of the DN doesn't look right. It should be:
cn=admin,dc=mydomain,dc=edu
Other than that, make sure the new server can reach the LDAP service. I.e., check routing, firewalls, antivirus software, etc. on the Moodle server, the LDAP server and all the networking devices in between them.
Saludos. Iñaki.