I have not encountered this issue since putting the CEM40 on a dedicated, unpowered, usb hub. I had the CEM40 going through a USB3.0 powered 12v hub, the same hub all my other gear was going through, and encountered this issue constantly, to the point of it not really being usable. I tried many different cables but it was always the same result.

I couldn't put the CEM40 directly into the Pi because the USB controller used in the CEM40 is not compatible with linux. I instead got a cheap USB2.0 unpowered hub off Amazon and connected it through that as this gets around the non-compatible controller issue, and since then I have zero subsystem crashes. It appears that something with that powered hub was not happy with the CEM40, and it caused the whole thing to go down.

If you have a similar issue the cheap USB2.0 hub is a good bet and doesn't cost much more than a new cable to try.

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