@cjiwonder It may help if you tell us what model of PC you’re trying to boot. There may be a BIOS setup option that needs adjustment.
For example, my Dell 3430s’ BIOS setup requires the following boot options:
General -> Boot Sequence: Onboard NIC(IPV4) (checkmark to enable)
General -> Boot Sequence: UEFI (checkmark to enable)
AND “Onboard NIC(IPV4)” must be the first device in the boot sequence list
But I must also have the following options in different menu set:
System Configuration -> IntegratedNIC: Enable UEFI Network Stack
System Configuration -> IntegratedNIC: Enabled w/PXE