I am authing both of these devices via user derivation rules. Both devices will connect for a couple minutes and then traffic will no longer pass between the device and AP. The controller still sees the device as associated and authenticated. Below is what I'm using for the dhcp-option for the user rules.
37012103060f1c333a3b - Kindle Fire
370103060f1c21 - Nintendo 3DS
Any ideas or known fixes?