dmesg | grep ath9k
Before attempting to download or install any driver for the TL-WN722N, you must check the Hardware Version (H/W Ver) printed on the sticker on the back of the device.
This is the most important step because TP-Link changed the internal chipset of this adapter, making newer versions incompatible with older drivers. tp tl-wn722n driver
You do not need to install anything.
The driver (ath9k_htc) is built directly into the Linux kernel.
Troubleshooting v1: If it isn't working, update your kernel: sudo apt update && sudo apt upgrade linux-image-generic dmesg | grep ath9k
Windows Update often installs a "generic" Microsoft driver that provides basic internet connectivity but disables the advanced features (like monitor mode or even the hardware LEDs).
Official driver download:
If Windows auto-installs a broken driver:
"The driver won't install on Windows"
"Device not recognized in Kali Linux"
"Where is the CD?"