Thanks for the clarification. The error is occurring before we reach the Fog menu.
The dhcpd.conf file shows several class definitions and most of them point to ipxe.efi.
I’m not using uefi on these laptops; they are all set to Legacy boot. I set the Legacy class file option to ipxe.kpxe …
AND IT WORKED. Ah ha! I understand better now.
Thanks so much for the help.