Before downloading anything, you must check the version number printed on the sticker on the back or bottom of the adapter.
Why this matters: A driver for V1 will not work for V2/V3, and vice versa.
For TL-WN722N V1 (Atheros AR9271):
For TL-WN722N V2 (Realtek RTL8188EUS):
This usually means the wrong driver is installed.
Error: “Device cannot start (Code 10)”
Error: “The driver may be corrupted or missing”
Driver works but no networks found
We will use a popular driver repository (like aircrack-ng compatible drivers) that enables monitor mode.
git clone https://github.com/aircrack-ng/rtl8188eus
cd rtl8188eus
sudo make
sudo make install
sudo modprobe 8188eu
Note: If make fails, ensure your kernel headers match your current kernel version exactly.
You are lucky. It works out of the box 99% of the time.
sudo apt update
sudo apt install firmware-ath9k-htc
sudo modprobe ath9k_htc
Plug it in. Done.