Linux driver for RTL8814AU
Don't buy this hardware
First, a word of warning if you are thinking of buying a product with this chip in: don't,
unless you are prepared to put a considerable amount of work in yourself.
More generally, don't buy any hardware that is not supported by the mainline kernel.
Some companies claim
Linux support on the box, on the basis that
some third party hosts some (likely unsupported and unmaintained) driver source code
for an antiquated kernel version.
If you have the choice, look for better alternatives.
If you need to use the Realtek RTL8814AU chip, such as the TP-Link Archer T9UH USB WiFi dongle, read on.
Prepare the Linux Source
In most cases it is sufficient to install the distribution's kernel-dev or kernel-headers package.
If you don't have the distribution's header files, you have to prepare the Linux source tree. Download or checkout a Linux version. In the Linux source tree, write:
Build the Driver
Download the RTL8814AU Linux driver from GitHub. The code should compile for kernels up to v5.2 (and possibly later) and will build the driver 8814au.ko.
In the rtl8814AU source directory, compile the driver as:
make clean all KSRC=<path-to-your-kernel-source> KVER=<kernel-version> sudo make install
The code was based on Diederik de Haas' repository which is based on version 4.3.21 of an Edimax driver for the EW-7833UAC device.