Change your boot filename to ipxe.efi
Some systems (pfsense) might have a different option for UEFI 32/64 bit file name. Change it to ipxe.efi.
Which file to use?
The FOG wiki suggests ipxe.efi should work for most systems.
Check IPXE column in the Devices table on the WorkingDevices FOG wiki page for tested filename.
You can get a list of all available files on your fog server in the /tftpboot directory
Change DHCP option 67 from undionly.kpxe to the new UEFI file you want to use.
Some systems (pfsense) might have a different option for UEFI 32/64 bit file name.
You may need to disable secure boot on some systems to boot correctly. It is recommended to turn this back on after imaging.