In a QubesOS configuration using two distinct VMs for handling USB and network (aka sys-usb and sys-net respectively), beware not all ethernet/wifi USB adapters are supported when you attach them to another VM than the USB one (aka sys-usb).
When attaching the USB adapter with following command issued in dom0: qvm-usb attach sys-net sys-usb:XXXX (where XXXX represent the device ID retrieved from qvm-usb)
then you can see ouput below from dmesg in sys-net: sudo dmesg:
More details at with some working USB adapters at: QubesOS/qubes-issues#3778.