What can I do to troubleshoot this? OpenLDAP client says ldap_simple_bind Can't contact LDAP server but it can resolve the name, ping the server, connect to port 636... and I have no details as to why it thinks it cannot contact the server. Many other clients authenticate to the same server, and I'm using the same ldap.conf, nsswitch.conf, and pam.d/system-auth files.