Internet Speeds Dropped 90%

Over the past two weeks internet speed dropped 90%. I've made no major changes to my machine.
I've added a new gaming mouse. And I went into BIOS to study some settings, but exited making no changes. (I, er, think.)
I've run Malwarebytes, Windows Defender full and offline scans. No malware found
I've also run the Tweaking.com's windows repair utility.
Checked on another machine in same room. Speed there is normal. Took THEIR wifi card and plugged it into my machine, plugging the suspect card into the other computer. No change. My machine was still slow. The other machine is still normal.
I'm starting to think it's hardware related. Nothing showing up in Device Manager, though.
Suggestions?
Joe Bonnar

 

Resolved.
I suddenly realized that I'd connected all wireless cards into the same USB port while testing things. (This was on a USB hub.)
Guess what happened when I changed port?
I blush, verily I blush.