I have never had any luck capturing anything useful with Wireshark in monitor mode. It seems to be a problem with capturing high speed WLAN frames. In a previous post I detail the problems I had with my WLAN adapter not being abe to capture all packets unless I downgrade the AP from 802.11n to 802.11b/g.
Assuming that this was the case, I have recently purchased an Alfa AWUS036ACM AC1200 WLAN adapter. This is the card recommended by aircrack-ng as the best card for wireless packet sniffing. However, I still have the SAME problem, I can only see low-rate frames over the air.
Please, can someone tell me is it actually possible AT ALL to capture the high rate frames of 802.11n and 802.11ac, and how I can troubleshoot this issue?
NOTE: I have no trouble setting this device into monitor mode. It sees frames from other stations, just not the ones I need. Decryption works fine too.