The special configuration required for the virtual machine that simulates the U disk:
1. Select the model as q35
2. Enable SeaBIOS, or select UEFI and enter BIOS to turn off secure boot
3. Cancel all Boot Order under Options
4. /etc/pve/qemu-server/101.conf
Add the following line in (note to modify the mirror path) :
args: -device 'nec-usb-xhci,id=usb-bus0,multifunction=on' -drive 'file=/path/to/arpl-sa6400.img,media=disk,format=raw,if=none,id=drive-disk-bootloader' -device 'usb-storage,bus=usb-bus0.0,port=1,drive=drive-disk-bootloader,id=usb-disk-bootloader,bootindex=999,removable=on'Source: https://blog.jim.plus/blog/post/jim/synology-sa6400-with-i915