Configuring a Pi4 for network booting:
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Download v1.16 release from github.com/pftf/RPi4
Extract files to SD card with one FAT32 partition.

Edit config.txt and setup a video mode that all your screens will support.
Other wise if the PI boots up while the screen is off it will be in a mode that no screen supports.
See Raspberry PI Config.txt
Example video mode 1360x768:

  hdmi_force_hotplug=1
  hdmi_group=2
  hdmi_mode=39

This will boot the Raspberry PI into a UEFI system to perform proper PXE Network Booting.
You will need to press ESC to enter setup and delete all boot options except for PXE UEFI IPv4.

Notes:

  v1.17+ is broken (grub will print "can't send network packet")

  The Raspberry PI4 does include network booting that is disabled by default, but is non-compliant.
  It identifies itself as a BIOS-x86 system (type 0) during DHCP discovery.
  This is probably because it is NOT UEFI but some proprietary boot process, which there is no identifier for.
  Also the images from raspberrypi.org and raspi.debian.org will kernel panic frequenently when used for PXE booting.
  jfNetBoot supported this custom boot process during early development but now requires the UEFI drivers instead.

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