Selecting a minimum bit rate of 12Mbps or higher will keep out 802.11b clients and increase the efficiency of the RF environment by sending broadcast frames at a higher bit rate.
It is recommended to set the minimum bit rate to 12 Mbps for a standard environment and 24 Mbps for a higher density environment. If a client device supports a maximum rate below the minimum base rate, it will not be able to connect to the AP. As stated above, this allows keeping older devices off a network to increase the efficiency of current client devices.
Low data ratesYou must carefully plan the process to disable or enable data rates. If your coverage is sufficient, it is a good idea to incrementally disable lower data rates one by one. Management frames such as ACK or beacons are sent at the lowest mandatory rate (typically 1 Mbps), which slows down the whole throughput, as the lowest mandatory rate consumes the most airtime. Try not to have too many supported data rates so that clients can down-shift their rate faster when retransmitting. Typically, clients try to send at the fastest data rate. If a frame does not make it through, the client will retransmit at the next lowest data rate and so on until the frame goes through. The removal of some supported rates helps the clients that retransmit a frame to directly down-shift several data rates, which increases the chance for the frame to go through at the second attempt.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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