Here is tutorial “How to update bootloader on Vu+ Duo 2” originally made by Pheonix from ViX team.

What do you need?

1. USB stick formatted to FAT32. It is recommended that you use HP Format Tool which is freely accessible on the internet.
2. VU+ Duo2 bootloader v2 (Duo2_CFE_V2.zip).

Proccess explanation

1. Format your USB stick to the FAT32 format using HP Format tool.
2. Extract the contents of the bootloader file to your desktop.
The bootloader once extracted will look like this
vuplus
vuplus/duo2
vuplus/duo2/cfe_cfe_auto.bin
vuplus/duo2/cfe_cfe_auto.md5sum
vuplus/duo2/cfe_cfe_auto.model

3. Copy the entire vuplus folder and its contents directly to the root of your USB stick.
4. Fully power down your receiver via the rear power switch.
5. Insert the USB stick containing the bootloader files into your front USB port and power on the receiver.
6. When instructed press the power button on the front of the receiver ( located behind the front flap on the front of the receiver) to initiate the flashing procedure.
7. If all has gone as expected you will see the message “Finished..reboot” at this point you can remove the USB stick and reboot your receiver using the rocker switch again.

Remember that at the moment upgrading bootloader is not mandatory. Update it only if you want WOL function which is why new bootloader was released.