@a_bains make sure you are using the instructions that say for both bios and uefi systems. https://forums.fogproject.org/topic/10944/using-fog-to-pxe-boot-into-your-favorite-installer-images/15
You do need to export the ISO to the files. The only way you can get the iso to boot is via memdisk in bios mode. UEFI doesn’t support memdisk booting.