Errors, bugs and logs

WiFi Invalid Channel

Using Cisco access points with CleanAir function you might come across this alarm. It means that the CleanAir chip have detected an access point using a frequency that is more than 500KHz off the specified frequency for the channel.

When this happens a normal AP or client will not be able to detect the signal. Two things is relevant in this case. First this enable a possible hacker to implement an invisible network. I.E placing a rogue AP on the network and connect to it from outside the building. It can also be caused be cheap or defect wireless equipment. Not necessary  Wi-Fi. Could also be a sound or video system. The effect is that this equipment will interfere with legal “on channel” equipment like your Wi-Fi network.

BUT! Be aware that many of these alarms from CleanAir can be caused be general high Wi-Fi congestion resulting in CleanAir “getting it wrong”.

My recommended action.

  • Start by eliminating possible false alarms caused by checking general wifi performance. Channel overlap, data rates and the likes.
  • Search for the interfering device using a laptop with a spectum-expect adaptor or a battery powered AP with CleanAir.
  • If the source of the interferer is impossible to trace. Like it’s just no special place an searching around make no logical difference it likely to be a false alarm.


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