How to install drivers for Realtek RTL8811AU? Ubuntu 21.04, kernel version - 5.11.0-16.17? Tried multiple versions from github but the problem has not been solved.

I figured out the utility of RTL8812AU driver for RTL8811AU chipset. You may try installing dkms (dynamic kernel module) of that driver by the command sudo apt install rtl8812au-dkms

Try this - for me it helped:

sudo dkms remove rtl8812au/5.7.0 --all
sudo dkms remove 8812au/5.6.4.2_35491.20191025 --all
sudo dkms remove 8812au/5.9.3.2_37279.20201012 --all

Then you can install the package with following commands:

sudo add-apt-repository "deb http://ppa.launchpad.net/kelebek333/kablosuz/ubuntu focal main"
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 23E50C670722A6D9
sudo apt update
sudo apt install rtl8812au-dkms

From TPLink Archer t2u+ & Kernel 5.10 (rtl8812) on Linux Mint Forums

Linux 5.10+

(Debian Bullseye and Ubuntu Focal onwards)

…currently requires a patched version of the rtl8812au driver. It worked for me on Debian and you may use that modified version as long as no "official" solutions are available.

You can download it from here* and it will appear in $ sudo dkms status as module 8812au version 4.2.3. Load it using $ sudo modprobe 8812au and after a few seconds your card should appear. Don't trust the reported connection quality, go near your router and if it does not connect automatically, reconfigure the connection manually. The driver will be recompiled automatically when a new kernel is installed but check if the connection works with the new kernel before removing the old ones.

_{*unofficial/unstable, do not use in production. Instructions included in the readme.}