@pacodijou You likely need to rethink how FOG operates.
The fact that you got into FOS itself (which is where you’re at) at least shows DHCP is working and passing the Options 66/67 appropriately, but it’s failing to get access to the fog server.
Based on what I can see, the DHCP items are working properly, assuming 192.168.75.10 is the fog server since that’s also where it’s trying to connect to look for access directly to the fog server.
Do you access the fog server at url:
http://192.168.75.10/fog/index.php?