@redbull007 Understood not fog. But where in the process is it failing.

PXE Rom requests dhcp address
PXE Rom DORA sequence where it gets the boot server and boot file
PXE ROM downloads the boot file from the boot server
iPXE starts up
iPXE Requests dhcp address.

If its in the iPXE then I thought of a test we can do

The tcpdump from the fog server point of view will tell us what the target computer is exactly asking for. That is the logic why to use it there. The test gives the best details if the target computer and fog server are on the same subnet to grab the packet capture.