@sebastian-roth Thanks for your help! that solved it:
in www-error.log I have and endless list of these errors:
[28-Jan-2021 11:23:41 UTC] PHP Fatal error: Uncaught Exception: Error multiple hosts returned for list of mac addresses in /var/www/html/fog/lib/fog/hostmanager.class.php:209
Stack trace:
#0 /var/www/html/fog/lib/fog/fogbase.class.php(571): HostManager->getHostByMacAddresses(Array)
#1 /var/www/html/fog/lib/client/registerclient.class.php(46): FOGBase::getHostItem(true, false, false, true)
#2 /var/www/html/fog/lib/fog/fogpage.class.php(3013): RegisterClient->json()
#3 /var/www/html/fog/lib/fog/fogpage.class.php(249): FOGPage->requestClientInfo()
#4 /var/www/html/fog/lib/pages/dashboardpage.class.php(76): FOGPage->__construct('Dashboard')
#5 /var/www/html/fog/lib/fog/loadglobals.class.php(67): DashboardPage->__construct()
#6 /var/www/html/fog/lib/fog/loadglobals.class.php(81): LoadGlobals::_init()
#7 /var/www/html/fog/commons/base.inc.php(49): LoadGlobals->__construct()
#8 /var/www/html/fog/management/index.php(22): require('/var/www/html/f...')
#9 {main}
thrown in /var/www/html/fog/lib/fog/hostmanager.class.php on line 209
looking at the date in c:\fog.log (or access_log on the server)
http://172.16.1.2/fog/management/index.php?sub=requestClientInfo&mac=00:FF:3E:84:3E:C1|40:A8:F0:61:47:B3&newService&json
We see two macs being posted. One this the mac of acual NIC in the machine, the other is for a VPN client.
The MAC for the VPN client is identical on all machines, and, by mistake, that mac got linked to a host in FOG. I removed the incorrect MAC from the host config and things started working again!
thanks again!