I have an older Mac mini I wanted to turn into a wireless sniffer with Wireshark, to decrypt WPA for some troubleshooting. This is not to hack anyone--it's to determine who is grabbing all of the bandwidth and WHY, so I need the IP headers.

On my Mac laptop I can put the wifi interface into monitor mode and it works fine, but then I can't use the laptop. So I have this Late 2012 Mini. Although I can put it in monitor mode, it will not decrypt even though it's set up identically to my laptop. I assumed the wifi card was the issue, so I bought this T2U Plus, but monitor mode isn't an option for it within Wireshark.

Is there a way to get this mini to see the T2U Plus as a true Wifi Nic capable of monitor mode? Or is that just not supported?