While Halikey on my Windows 10 box just worked, my Windows 11 machine had forgotten that serial ports had ever existed.There's a fix for this online, but it took me a bit longer than I thought to go through the driver update process. The steps were outlined here . (I used the answer from RobinsonSilvestre. I can't find a way to link to that exact response. Just in case, I've also copied the response below.) The very first step was to find my Halikey in the Windows Device Manager. For me, it appeared under "Other devices". I figured this out by counting the number of entries in "Other devices" before and after I plugged in my Halikey. With my Halikey attached to a USB-C drive, my count of rows went up by one. I determined which entry was new, (I can't remember the name, or I'd document it here), I figured out which device to right click on to update the driver for the Halikey so I could follow the above linked procedure. Next, I found the driver...