ConbeeII keeps disappearing in KVM-virtual machine

Dear all,

Since 1st of December I have the problem that phoscon in my home assistant cannot connect to conbee firmware any more.

My setup:
Core i3-8100 debian 11.5 (uo to date) VM-host
libvirt virtualization
HAOS in virtual machine with 2 cores and 4 GB of RAM.
conbeeII connected by extension cable to USB2 Port

Stable service till 1st of December 22.

Now conbeeII is recognized on USB but phoscon shows firmware not connected.

conbeeII connected to Windows 10 PC connects and shows firmware.

conbeeII in another VM with fresh install of debian 10 or 11 and deconz installed shows in deconz 1-2s “connected” before button gets greyed out.

Does anyone have any suggestions? I am totally in the dark (literally).

Firmware was updated to latest version on Windows 10. No change.

Best regards,

Marco