I bought two of these to provide WIFi to a Raspberry Pi 4B and a Raspberry Pi 3B. Although the Pi4B has built in Wifi the case the Unit was mounted in provided shielding to the WiFi. So, this ended up being the solution. After reading all the instructions, there were a number of software issues. However, changing the repository (5) to .../morrownr/8821cu.git and just followed (8) Install the driver it just works straight away on a Pi 4B and Pi 3B :-). The range is brilliant without the aerial extension. I'm connecting further away than any other device I've got.