Also,
to check for the bss-minrate you can use CLI:
SSH in
show wlan - will show all the options for each WLAN, including bss-minrate
tochange bss-minrate:
config
wlan "Name of your WLAN"
bss-minrate - to change the bss-minrate
exit - to save the config
ZD 10.x.x might have this under WLAN->Advanced config in the GUI as well