Recently I installed Home Assistant on my new HP ProDesk 400 Mini G9. I wanted to passthrough the built-in Bluetooth adapter (Intel AX211 Bluetooth, USB ID 8087:0033) from Proxmox to the Home Assistant VM.

I thought it would be as simple as passing the device through in Proxmox, but Home Assistant didn’t recognize the adapter. In the HA logs I kept seeing errors like “Bluetooth fw download failed.”

Proxmox Bluetooth screenshot

After some research, I found that the Proxmox host was still interacting with the Bluetooth adapter, even though it was assigned to the VM. Because of this, the firmware could not be loaded by Home Assistant.

Workaround#

Blacklist all Bluetooth-related kernel modules on the Proxmox host so it stops touching the device:

# /etc/modprobe.d/blacklist-bluetooth.conf
blacklist btmtk
blacklist btusb
blacklist btintel
blacklist btbcm
blacklist bluetooth
blacklist btrtl

Then rebuild initramfs:

sudo update-initramfs -u -k all

Reboot the host. After reboot, verify that no Bluetooth modules are loaded:

root@proxmox:~# lsmod | grep -E 'bluetooth|btrtl|btmtk'
root@proxmox:~#

After this, Home Assistant instantly recognized my Bluetooth adapter and everything worked correctly.