There was a regression in the kernel with the RT driver, see
https://ask.wireshark.org/questions/53260/cannot-capture-frames-other-than-broadcast-or-multicast-over-wlan
for some discussion. It looks like the 4.4 series kernel fixed it, at least on x8...
https://ask.wireshark.org/questions/53260/cannot-capture-frames-other-than-broadcast-or-multicast-over-wlan
for some discussion. It looks like the 4.4 series kernel fixed it, at least on x8...