Comment 10 for bug 1637059

I found that this driver does NOT support some USB devices based on the 8821au (since the Debian/Ubuntu source lacks some HAL files) and USB device IDs.

In my case:
$ lsusb

Bus 001 Device 109: ID 0bda:0811 Realtek Semiconductor Corp.

I found a working driver (based on later (4.3.14) upstream source) that can also be built and installed via DKMS at:

https://github.com/abperiasamy/rtl8812AU_8821AU_linux

which builds the module rtl8812au.ko