System Log > Wireless Log > Wireless 5 GHz
Channel will also display width (80 for example)
Streams will display 802.11ac streams (usually 2)
Rx/Tx will display link rate (866 for example)
QAM can only be inferred
@coxhaus - Thank you for the recommendation. It looks like I have my Arris modem/router running in modem bridged mode. If I have any trouble with it I'll definitely get the SB8200.
@EmeraldDeer - Yes, it looks like I'm running in 2x2 AC mode (866 link rate). Based on other numbers reported I think 640Mbps is about what you can get unless you go to a 4x4 AC adapter or a 160MHz one. Actually, a new Intel Ac-9260 is only around $20 or so...