When I tried to connect the calculation PC (Ubuntu 20.04 LTS, self-made) to the net, I searched variously, but I left a record here because the information was old and there was only information that was out of print. Let's keep it. It will be updated from time to time.
PLANEX GW-450D2 In Ubuntu 18, I installed the driver and moved it by referring to here, but the operation was unstable. I used to cut it well ... However, with Ubuntu20.04LTS, I was able to recognize and connect just by inserting it. There is no disconnection.
-BUFFALO AirStation Wifi repeater, connected to PC with LAN cable. It is necessary to set Wifi on another PC (Windows etc.). Instead, no settings are required on the Linux side.