There is an issue in the 4.9.x kernel which seems to crash USB 3.0 when external drives are under very heavy loads. In my case I used a USB 3.0 Stick which delivers up to 245 MB/s.
If I executed
$this->bbcode_second_pass_code('', 'dd if=/dev/sda of=/dev/null bs=1MB ')
and had high utlizitation on the network the drive crashed with
$this->bbcode_second_pass_code('', 'reset SuperSpeed USB device number [...]')
which did not always recover successfully. This seems to be fixed in 4.14.x - at least I haven't gotten a crash until now. Another option would be 3.10, but in that version USB 3.0 is a lot slower (~220 MB/s vs. 120 MB/s).
Please upgrade the Kernel to 4.14.x. Thanks!
I am definitely not alone with this issue: https://www.google.at/search?q=%22xu4%2 ... +number%22
Possibly related: https://github.com/hardkernel/linux/issues/120