@gothikserpent Well I’m glad you have a workaround but really the issue is what your dhcp server is telling your client computer on the networking side. As I said in chat I don’t know how a computer placed on that subnet can communicate with any other subnet.
In the case of dnsmasq and isc-dhcp server running on fog. They are configured to dynamically switch the boot file name based on the pxe booting computer’s mode. If the pxe booting computer is in bios mode both dnsmasq and isc-dhcp will send undionly.kpxe boot file, if the pxe booting computer is in uefi, both will send ipxe.efi. In the case of these two services they are able to adapt to the format of the pxe booting computer.