Using the Conbee III as a Zigbee Gateway in Proxmox based Home Assistant VM

This is quite a niche topic, but given how hard it was to find a complete explainer on this combination of services/devices, I thought I would put it up. Even, if it just helps me in the future when I predictably break the system and need to reset it. Thanks to this other article, for giving me a good starting point.

TLDR

It is possible to use the Conbee III as your Zigbee Gateway for Home Assistant running in Proxmox as a VM. The overview of steps is the following.

  1. Install Home Assistant as a VM using this helper script.
  2. Flash the deCONZ_ConBeeIII_0x26450900.bin.GCF firmware onto the Conbee III using GCFFlasher.
  3. Plug the device into a USB2 (not USB3) port in your Proxmox server.
  4. Pass the USB device to your VM in the Proxmox GUI, under Hardware.
  5. Reboot Home Assistant.
  6. Add the Zigbee Home Automation (ZHA) integration.
  7. Add devices.

Background

I have been wanting to start self-hosting for a while, but, unfortunately, I was very focused on non-self-hosting as a job. Not anymore! And now I have some time to give it a try. Separately, as if a sign from a greater being, a 10 year old Dell Workstation appeared outside my house. I do love "Zum Verschenken" culture. I didn’t need anymore pushing.

Proxmox

I have spent the last 4 years working on the AWS EC2 Nitro Hypervisor, which is probably one of, if not, the most commonly used KVM based hypervisors, so I was excited to try out another KVM based hypervisor. Also, I did not want to deal with dependency hell with multiple services running on the same host. There is nothing like the feeling of clicking “Delete VM”.

Luckily, there is an amazing collection of scripts which make starting things in Proxmox super easy. And yes, these are random scripts off the internet, so you should definitely go read them, but not run them locally, or do, I am not your parent. I installed Home Assistant into a VM and within minutes I had it running. Great!

Actual Problem to Solve

My partner had been asking for months for some under-shelf lighting for our sink. Luckily, a friend was making the trek to Ikea, and offered to pick up some lights for me. I went with the TrÄdfri system, and the key part was the "Driver for wireless control, smart gray, 10 W" along with a 80cm LED strip. This setup turns on automatically when not connected to a network, so, immediately, we had a working solution, but, obviously, not optimal. You had to pull it out of the socket in the wall to turn it off. I needed a gateway and switch to get this working well.

Zigbee Gateway

There are many options recommended by the Home Assistant community, and I probably should just have gone with the TrĂ„dfri Gateway, but I didn’t want to use Ikea’s internet-connected app. I live in Germany, so I used the Dresden Elektronik Conbee III.

To get this gateway to work, I had to try multiple firmware versions. Most likely, the reason it wasn’t working initially was because I was plugging it into a USB3 port rather than a USB2 port. But, I did get it to work with the deCONZ_ConBeeIII_0x26450900.bin.GCF version of firmware.

Flashing the Conbee III

You will need to download GCFFlasher and a new firmware version, I found that the deCONZ_ConBeeIII_0x26450900.bin.GCF version works, but it is from 2023, and there are a couple new ones. Once you have GCFFlasher downloaded, you can find which USB device to target with the following command. 

$ ./GCFFlasher -l

And then you can flash the device with:

$ ./GCFFlasher -d /dev/ttyUSB0 -f ./deCONZ_ConBeeIII_0x26450900.bin.GCF

Make sure to let it fully complete and validate before disconnecting the Conbee III.

Device Passthrough in Proxmox

There are two ways to enable USB device passthrough, which is needed to access the Conbee III in the Home Assistant VM. First option, is to use the pre-installed qm tool. 

$ dmesg | grep tty # This will give you the ttyUSBx you need to use, mine was ttyUSB0
$ qm set 100 -usb0 /dev/ttyUSB0 # the 100 is my Home Assistant's VMID

Or, you can use the GUI in the Proxmox dashboard. Proxmox VMs have a Hardware section, and in there you can enable the USB device passthrough (Hardware->Add->USB Device).

Either way, you will need to reboot your VM to persist the changes.

Setting Up ZHA with the Conbee III

Once you have the correct firmware installed, you will need to plug the Conbee into a USB2 port. It is recommended that you use a USB extender to reduce interference, but I didn’t have one handy, and it hasn’t been a problem so far with a couple devices connected to the network.

Once the device is plugged in, you can select the Zigbee Home Automation plugin under Devices & Services in the Home Assistant settings. It should detect the Conbee III automatically, since the Conbee III has been supported since early 2024. I have not gotten it to work with manually selecting the port.

Connecting the Wireless Light Receiver

This is relatively easy. The wireless receiver has a small hole on one side which says reset next to it. If you select “Add Device” in ZHA and then hold the reset button down for a couple seconds, the receiver will pop up in ZHA, this was done while the two devices were meters from each other, you do not need to be close.