Authentication

I don't see anything wrong in your settings, except the ldap_memberattribute, which should be 'member' instead of 'memberof'. But given that authentication only uses this attribute to assign course creator role, this shouln't be an issue for authentication itself.

Maybe you could add the following lines (the ones marked) to your moodle/auth/ldap/lib.php file to try and diagnose the problem:

    if ($ldapconnection) {
        $ldap_user_dn = auth_ldap_find_userdn($ldapconnection, $username);

        error_log ("username: |".$username."|,ldap_user_dn: |".$ldap_user_dn."|");   /// <---- Add this line.

        //if ldap_user_dn is empty, user does not exist
        if(!$ldap_user_dn){
            ldap_close($ldapconnection);
            return false;
        }

        // Try to bind with current username and password
        $ldap_login = @ldap_bind($ldapconnection, $ldap_user_dn, stripslashes($password));
        ldap_close($ldapconnection);
        if ($ldap_login) {
            return true;
        }
    } else {
        @ldap_close($ldapconnection);
        error("LDAP-module cannot connect to server: $CFG->ldap_host_url");
    }
    error_log ("username or password incorrect");   /// <---- Add this line too.
    return false;

This will add some logging info to your PHP logs which will enable us to see why new user logins are failing.

Saludos. Iñaki.