Just so I’m clear, the 440s pxe boot just fine to the FOG iPXE boot menu is that correct.
But the problem comes when the timeout on the iPXE menu reaches 0 it doesn’t boot from the hard drive? It tries to just pxe boot again, like the target computer just rebooted and never loads from the hard drive?
If this is true, then your exit mode from FOG is not set correctly. 90% of the time SANBOOT works great for locating the hard drive. Other times not so good. What I would do is change the bios exit mode from one system to the other FOG exit modes to see if it can locate the hard drive.
The other option is if you don’t need unattended imaging, you can always set the format to be usb,ssd and then when you want to image (you have to be in front of the computer) but boot the computer and press the F12 key to get the boot menu. From there you can pick network boot.
You can also leave the target computers in uefi mode if you just disable secure boot and then send the uefi kernel [ipxe.efi] to the target computer. But of course you must have a uefi based system image to deploy to that target computer.