Hi Paul
Thanks for pointing out . I checked config-dist.php but missed it. So '$CFG->site_is_public = false;' answers my question. Thanks a lot.
P.S. The flurry of off-topics: Leaving all the "non-scientific" guess work aside, if this hub/errorconnect develop to be a (new) frequent problem, it will be a hard one for most of the newcomers because it requires deletion of information on either side - in Moodle and in HQ. As Ken already pointed out, this is future. It is fully OK with me to leave the future alone.