For anyone still looking for the answer in Big Sur. I manage to make it work using the latest drivers, the "beta" version for Big Sur in the ASIX page:
asix.com.tw/en/product/usbethernet/super-speedusbethernet/ax88179
It is important to follow the instructions in the readme inside. And after you install and reboot, open the ASIX DEVICE APP that has been installed along with the drivers. There you activate the device.
Hope it helps.