HAOS 18.3 regression: Realtek RTL8761 USB Bluetooth (0b05:1bef) repeatedly disconnects on OVA/Proxmox, works on 18.2

Description

After upgrading Home Assistant Operating System from 18.2 to 18.3 on an OVA running under Proxmox VE, an ASUS USB Bluetooth adapter based on Realtek RTL8761 stops working.

The same adapter, same physical USB port, same Proxmox VM configuration, and same Home Assistant Core version work correctly on HAOS 18.2.

Environment

• Home Assistant OS 18.2: working
• Home Assistant OS 18.3: failing
• Home Assistant Core: 2026.9.3 in both tests
• Installation type: OVA / Proxmox VE VM
• USB adapter:
  • Vendor/Product ID: 0b05:1bef
  • Manufacturer: Realtek
  • Chip reported by kernel: RTL8761
• Proxmox USB passthrough:
  • usb2: host=3-1
• Bluetooth controller MAC when working:
  • A0:AD:9F:6F:1F:EE

Reproduction / A-B test

A clean A/B test was performed using the same hardware and VM configuration.

HAOS 18.2

1. Fully shut down the Home Assistant VM.
2. Confirmed on the Proxmox host that the adapter returned to the host and initialized successfully as: Port 001 ... Class=Wireless, Driver=btusb, 12M
3. Re-applied the same passthrough configuration: qm set 101 -usb2 host=3-1
4. Started the VM on HAOS 18.2.

Result:

• bluetoothctl list shows: Controller A0:AD:9F:6F:1F:EE homeassistant [default]
• Bluetooth speaker reconnects automatically.
• Audio works normally.

HAOS 18.3

The exact same sequence was repeated:

1. Fully shut down the Home Assistant VM.
2. Confirmed the adapter initialized successfully on the Proxmox host with Driver=btusb.
3. Re-applied: qm set 101 -usb2 host=3-1
4. Started the VM on HAOS 18.3.

Result:

• Bluetooth controller never becomes available in Home Assistant.
• Bluetooth speaker does not appear/connect.
• bluetoothctl list is empty.

HAOS 18.3 kernel log

[    1.888556] usb 9-3: new full-speed USB device number 3 using xhci_hcd
[    2.038670] usb 9-3: New USB device found, idVendor=0b05, idProduct=1bef, bcdDevice= 2.00
[    2.039513] usb 9-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    2.040252] usb 9-3: Product: Bluetooth Controller
[    2.041304] usb 9-3: Manufacturer: Realtek
[    2.176062] Bluetooth: Core ver 2.22
[    2.176623] NET: Registered PF_BLUETOOTH protocol family
[    2.177241] Bluetooth: HCI device and connection manager initialized
[    2.178086] Bluetooth: HCI socket layer initialized
[    2.178763] Bluetooth: L2CAP socket layer initialized
[    2.179485] Bluetooth: SCO socket layer initialized
[    2.185279] usbcore: registered new interface driver btusb
[    2.194629] Bluetooth: hci0: RTL: examining hci_ver=0d hci_rev=000e lmp_ver=0d lmp_subver=8761
[    2.216058] usb 9-3: USB disconnect, device number 3
[   10.327190] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[   10.327194] Bluetooth: BNEP filters: protocol multicast
[   10.327198] Bluetooth: BNEP socket layer initialized
[   12.319540] Bluetooth: hci0: RTL: RTL: Read reg16 failed (-110)
[   12.790895] usb 9-3: new full-speed USB device number 4 using xhci_hcd
[   12.938882] usb 9-3: New USB device found, idVendor=0b05, idProduct=1bef, bcdDevice= 2.00
[   12.938896] usb 9-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[   12.938898] usb 9-3: Product: Bluetooth Controller
[   12.938901] usb 9-3: Manufacturer: Realtek
[   12.952446] Bluetooth: hci0: RTL: examining hci_ver=0d hci_rev=000e lmp_ver=0d lmp_subver=8761
[   12.978157] usb 9-3: USB disconnect, device number 4
[   23.491804] Bluetooth: hci0: RTL: RTL: Read reg16 failed (-110)
[   23.968086] usb 9-3: new full-speed USB device number 5 using xhci_hcd
[   24.115951] usb 9-3: New USB device found, idVendor=0b05, idProduct=1bef, bcdDevice= 2.00
[   24.115960] usb 9-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[   24.115961] usb 9-3: Product: Bluetooth Controller
[   24.115963] usb 9-3: Manufacturer: Realtek
[   24.127022] Bluetooth: hci0: RTL: examining hci_ver=0d hci_rev=000e lmp_ver=0d lmp_subver=8761
[   24.151805] usb 9-3: USB disconnect, device number 5
[   34.730954] Bluetooth: hci0: RTL: RTL: Read reg16 failed (-110)

Additional observations

• On HAOS 18.2, after the same cold shutdown / host re-enumeration / passthrough reapply procedure, the adapter works reliably.
• On HAOS 18.3, the adapter is visible to the guest initially, btusb starts RTL8761 initialization, then the USB device disconnects repeatedly and Read reg16 failed (-110) is logged.
• This does not appear to be a Home Assistant Core regression because Core 2026.9.3 is the same in both the working and failing tests.
• The failure occurs below Music Assistant / BlueZ application-level use; bluetoothctl list remains empty on 18.3.
• The adapter is healthy enough to initialize successfully on the Proxmox host before passthrough.

Expected behavior

The RTL8761 USB Bluetooth adapter should initialize on HAOS 18.3 as it does on HAOS 18.2.

Workaround

Boot HAOS 18.2, fully stop the VM, allow the adapter to re-enumerate on the Proxmox host, re-apply usb2: host=3-1, and start the VM.

If useful, I can provide additional dmesg, Proxmox VM configuration, or USB topology output.