I'm also using Wireshark to troubleshoot and this is what I've found:
1142 16.255135000 192.168.1.10 192.168.2.20 LDAP 111 bindRequest(1) "adminuser@mydomain" simple
1143 16.283321000 192.168.2.20 192.168.1.10 LDAP 76 bindResponse(1) success
1144 16.283549000 192.168.1.10 192.168.2.20 LDAP 129 searchRequest(2) "dc=my,dc=domain" wholeSubtree
1149 16.311655000 192.168.2.20 192.168.1.10 LDAP 499 searchResEntry(2) "CN=John Doe,OU=Users,OU=California,DC=my,DC=domain" | searchResRef(2) | searchResRef(2) | searchResRef(2) | searchResRef(2) | searchResRef(2) | searchResDone(2) success [1 result]
1153 16.316424000 192.168.1.10 192.168.2.144 LDAP 111 bindRequest(1) "adminuser@mydomain" simple
1154 16.317344000 192.168.2.144 192.168.1.10 LDAP 164 bindResponse(1) invalidCredentials (80090308: LdapErr: DSID-0C0903A9, comment: AcceptSecurityContext error, data 52e, v1db1)
1973 26.378798000 192.168.1.10 192.168.2.14 LDAP 111 bindRequest(1) "adminuser@mydomain" simple
1975 26.439360000 192.168.2.14 192.168.1.10 LDAP 76 bindResponse(1) success
1976 26.439637000 192.168.1.10 192.168.2.14 LDAP 147 searchRequest(2) "DC=DomainDnsZones,DC=my,DC=domain" wholeSubtree
1977 26.498631000 192.168.2.14 192.168.1.10 LDAP 76 searchResDone(2) success [0 results]2305 31.497416000 192.168.1.10 192.168.2.14 LDAP 61 unbindRequest(3)