We had an emergency call yesterday from an academic customer, all their Ipads were simultaneously downloading the new software and maxing out their Internet connection so nothing else could be done. It didn't seem to be possible to rate limit directly on their WLAN, so we ended up sticking a rate limit (shaping) on the switch port feeding the controller. There's got to be a better way, we've numerous times had customers reporting network-wide issues then found similar, normally Windows updates all downloading simultaneously and using all their WAN bandwidth.