Go back –> ath10k
ath10k supports monitor mode. Recommended firmware version for a sniffer is 10.1.467.2-1. Also use recent enough wireshark which supports 11ac.
To tune into 80 MHz channel, in this example channel 36 (5180 MHz):
ip link set wlan0 down iw wlan0 set type monitor ip link set wlan0 up iw wlan0 set freq 5180 80 5210
To capture HT40+ on channel 36:
iw wlan0 set freq 5180 40 5190