5. Use 40MHz-wide Channels Only with Strong Signals
This serves as a disclaimer for the above tip, about changing the default channel width to enable the higher data ratessometimes referred to as channel bonding. Though the effect can be great, it works only with users that have a good connection.
At a certain point, 40MHz-wide channels and a lowering signal will start to negatively affect the throughput. The worse the signal gets, the more negative its impact.
So if not all your computers are in a good range, you may actually consider leaving the channel-width setting alone.