Raspberry Pi 5 (16GB) never performs native Network Boot (no TFTP RRQ on port 69), only PXEClient DHCP, regardless of EEPROM configuration

[Frigo2010]

Describe the bug

Summary

A Raspberry Pi 5 (16GB) never performs native Raspberry Pi Network Boot
(start4.elf over TFTP), even with a correct EEPROM configuration.

The device always sends DHCP requests with Vendor-Class
PXEClient:Arch:00000:UNDI:002001
and never issues any TFTP RRQ on UDP port 69.

As a result, diskless PXE / NetBoot (TFTP-based) is impossible.

---

Hardware

• Raspberry Pi 5, 16GB RAM
• Ethernet boot only
• No SD / USB / NVMe attached during test
• Power-cycled between all tests

---

EEPROM / Bootloader

• EEPROM updated to latest available version (via rpi-eeprom-update)
• EEPROM config set using sudo -E rpi-eeprom-config -e

Confirmed EEPROM configuration:

BOOT_ORDER=0xf21
ENABLE_NETWORK_INSTALL=0
SIGNED_BOOT=0
NET_WAIT=1
NETWORK_TIMEOUT=45000
BOOT_UART=1
DISABLE_SELF_UPDATE=1



### Steps to reproduce the behaviour

1. Prepare a Raspberry Pi 5 (16GB).
2. Update the EEPROM using `rpi-eeprom-update`.
3. Test with both EEPROM firmware versions:
   - the default (stable) EEPROM release
   - the latest EEPROM release (`rpi-eeprom-update -a`)
4. Boot once from SD card with Raspberry Pi OS.
5. Edit EEPROM configuration using `sudo -E rpi-eeprom-config -e` and set:

   BOOT_ORDER=0xf21  
   ENABLE_NETWORK_INSTALL=0  
   SIGNED_BOOT=0  
   NET_WAIT=1  
   NETWORK_TIMEOUT=45000  

   Save and exit.

6. Power off the device.
7. Remove all boot media (SD, USB, NVMe).
8. Connect Ethernet only.
9. On another machine, run a DHCP + TFTP server (e.g. dnsmasq) serving `start4.elf`, `fixup4.dat`, `kernel8.img`.
10. Start packet capture on the server:

    `tcpdump -i <interface> port 69`

11. Power on the Raspberry Pi 5.

### Device (s)

Raspberry Pi 5

### Bootloader configuration.


EEPROM configuration (output of `rpi-eeprom-config`):

BOOT_ORDER=0xf21
ENABLE_NETWORK_INSTALL=0
SIGNED_BOOT=0
NET_WAIT=1
NETWORK_TIMEOUT=45000
BOOT_UART=1
DISABLE_SELF_UPDATE=1


The same behavior occurs when booting with:
- the default (stable) EEPROM firmware
- the latest EEPROM firmware updated via `rpi-eeprom-update -a`

The EEPROM backup stored in
`/var/lib/raspberrypi/bootloader/backup`
shows identical boot behavior.


### System

_No response_

### Bootloader logs

_No response_

### USB boot

_No response_

### NVMe boot

_No response_

### Network (TFTP boot)

_No response_

[timg236]

The Pi5 network boot behaves the same as Pi4 (it's the same software). Please post UART logs showing the problem.

N.B start4.elf is not relevant on P5 and NET_WAIT is not a valid config option