Unreliable USB: https://github.com/raspberrypi/linux/issues/3259
Unreliable Wi-Fi:
* https://github.com/raspberrypi/linux/issues/7092
* https://github.com/raspberrypi/linux/issues/7111
* https://github.com/raspberrypi/linux/issues/7272
I don't understand why many say that RPi software/firmware support is 'fantastic'. Maybe it used to be in the beginning compared to other chips and boards, but right now it's a bit above average: they ignore many things which is out of their control/can't debug and fix (as in Wi-Fi chip firmware).