What do the radio mode settings in the last column mean?
This shows the list of our 3 SSIDs that we use.What is the difference between a/n/g and a/n/g/n-strict mode?
Does this mean any device with a "a" or "n" or "g" radio can connect to this SSID?
It's an overview of the different modes used on that service. For example if you only selected a radio that was configured for G/N then that column would only show G/N. When you are logged into the controller there is a help file on the upper right hand side of the GUI. You can search that for your rate questions. Example:
a — Click to enable the 802.11a mode of Radio 1 without 802.11n capability.
a/n — Click to enable the 802.11a mode of Radio 1 with 802.11n capability.
a/n/ac — Click to enable the 802.11ac mode of Radio 1 with 802.11ac capability.
ac-strict — Click to enable the 802.11ac mode of Radio 1 with 802.ac strict capability.
n-strict — Click to enable the 802.11a mode of Radio 1 with 802.11n strict capability.