What worked for me, and the only solution I found was to add ALL external USB drives to Spotlight Privacy tab so it doesn't get indexed. I stopped having this issue after I did that.
You can't search the external USB drives anymore with Spotlight, but you can use something like
EasyFind to search it and it works well.
I'm not knowledgeable enough to fix this issue, but I have tried various USB inject methods and none of them fixed it so I went back to the one I was using previously (a custom USB kext).
Also personally I haven't tested an external USB SSD, only external Hard Drives. I get a lot of them here, sometimes G-Raid, Lacie, Western Digital, etc etc. All HDDs had the same issues for me, but the Spotlight workaround fixed it for me.
Losing Spotlight on external drives is not a big deal for me, I have external HDDs connected all the time and leave them in there for weeks to sometimes months, and I would get that error after a while.
This never happened to me on a real Mac.
It's odd it didn't work for you. Are you sure you added ALL external USB drives? Including Flash drives? (I haven't tested or noticed this issue on Flash drives, can't confirm).
The Spotlight workaround works perfect for me even after restarts. My machine's been on for weeks and drives connected for weeks. I come back and click on the drive and it "wakes up" fine and no eject issues. If I want to keep the drive running forever with no sleep (ie you come back even after a day, it will be instantly available) I use
Keep Drive Spinning and it works wonderfully. Its a simple script and I sometimes use it.
It's definitely related to something with the USB injection, but I haven't figured it out yet (or I just gave up haha). My Gigabyte BIOS isn't as deep as an Asus board, so I don't see an "Internal CPU PLL Overvoltage" anywhere in the Designare EX.
Thank you for keeping track of this, I know we both had trouble. I think I have given up and learned to live with it. I put the 2 antennas outside of the case and as far as possible from the rear of the computer which has a lot of USB 3.0 drives connected so there's less interference. (I'll post a pic soon).
For now, I have removed the kexts for the Broadcom chip that's on the Designare EX and I am using an older OSXWifi card from a couple of years ago. I had recently ordered the OSXWifi BT 4.1 module but returned it (Not sure if you remember this)...it didn't really help a lot maybe by 10%.
I also am sticking with OSXWifi for now because I'll probably get the space gray Apple wireless keyboard so I need to have it available during BIOS too (which the onboard modded module wouldn't allow).
Surprisingly those small USB adapters work well, but the range is pretty average, so that's why I stopped using it. I have one hanging around but I remember I didn't have audio stutters with those, just the range was bad.
Maybe use a
USB cable extension and tuck the USB adapter underneath your monitor? Or somewhere closer to your headphone so you have less interference since they don't have larger antennas.
As far as Windows, with the limited amount of time I use it nowadays (last time I booted into it was more than a month ago) the OSXWifi card seems to work OK as long as you extract the drivers from a Bootcamp installer....and then it works ok. I don't remember if I had similar stuttering issues with those.
This is all related to interference/bad shielding coupled with USB injector in macOS I think. If you remember, I posted a whitepaper about USB interference. Real Macs and even real PCs have good shielding on the BT/Wifi modules all around, so maybe that will be the best solution possible.
