Speeds

Disable low Data Rates

To turn off rates 1, 2, 5.5, and 11, you go into the CLI on the FortiGate and use the following:

config wireless-controller vap
      edit <vap_name>
              set rates-11a 12-basic 18 24 36 48 54
             set rates-11bg 12-basic 18 24 36 48 54
       end

Channels

Avoid 80+ MHz wide channels in 5GHz and only use 20 MHz channels in 2.4GHz. There are use cases for wider channels, but there is not enough spectrum available today for proper channel reuse in an enterprise deployment or a multitenant environment. You will end up with CCI and ACI (co-channel and adjacent channel interference).

Use the Widest Channel Available

Check your counteries DFS Channels – That means these have special rules and have to coexist with things like weather radar and military functions. When an AP detects a “hit” on DFS it has to change to a non-DFS channel for a specified time in order to free up that spectrum. In some places DFS is nearly unusable because of so many DFS hits. In many cases DFS is usable and frees up spectrum. This allows more channels which also means the potential for using 40 MHz wide channels because you have less chance of CCI and ACI.

 No 802.11b Devices = SGI (Short Guard Interval) On , otherwise Off. Use of 11b clients necessitates use of low (non-OFDM) data rates, which forces the use and ripple of protection mechanisms (e.g. RTS/CTS and CTS-to-Self)

Reduce SSID’s and Split Networks using Authentication methods ( Radius -> Corporate , Guest to Guest )