Ubuntu: Installing/fixing TP-Link AC1200 (T4UH 1.0) drivers in Ubuntu

[Updated instructions for Ubuntu 20.04 here] I have had this USB wireless adapter working fine on Ubuntu 18.04 LTS for a while. A system update stopped it from working. Re-installing the OS provided drivers (Software & Updates / Additional Drivers) made no difference. I tested the adapter in other operating systems and it worked fine.… Read More »