Supported data rates for clients may be modified per WLAN. Navigate to the Data Rates section under the WLAN configuration in template or site level WLANs.
The PHY header is always sent at the minimum supported PHY rate for the band, it’s important to remember that the clients have to decode the MAC header in order to understand the frame type, and that includes beacons and probe responses. The MAC header is part of the PSDU/MPDU and is sent at higher/configurable rates.
There are arguments for and against disabling low data rates but disabling lower legacy data rates will help your WLAN perform much better.
Compatible: Default option, Mist APs allow all clients to connect.
No Legacy: 11b and 11g clients will not be able to join the network. This option will prevent protection ripple, both of which will add capacity to your network.
High Density: Disallow 11b and 11g clients from trying to join the network, but only allow clients will a good signal level join, which could impact your roaming behavior.
While enabling High Density, in environments with older scanner or POS devices proceed with caution.
Custom Rates: Select from the below 5G data rates.
Most 5G capable client drivers have been written to accept any rate or set of data rates that an AP is announcing as Basic. Further still, there are a few 5G capable client drivers out there that will only accept 6, 12, or 24M, but nothing else. This is why 18M, when used as the only basic rate, may not be a good idea – as it will cause clients to not connect to the BSS.
There is great material available on the internet on this topic.
