2.4G wifi --- 20/40MHz operation not permitted on channel

I found this notice in syslog : 20/40 MHz operation not permitted on channel

  • as i understand this is due presence of many other 2,4G AP in range (over 30 AP around)
  • also seems when the channels are picked (primary/secondary), sum of both should not be over 15.
  • i found solution , using noscan = '1' in wireless uci config in device section (but they note that this is against regulatory rules), tried and it is working (at least no notice in syslog).
ht modes

HT40- (2x 20MHz channels, primary/control channel is upper, secondary channel is below)
HT40+ (2x 20MHz channels, primary/control channel is lower, secondary channel is above).
HT40 (2x 20Mz channels, auto selection of upper or lower secondary channel on versions 14.07 and above).

I was using HT40 without any issues till today (with auto for channels). Maybe HT40- might help to keep the sum of channels under 15 (will try tomorrow). For now i am using HT20.

I don’t think the following message solves your problem, but …

It is reported that in the disturbed environment of a large number of surrounding wifi and together with the effect of interference reflections of your station, the use of 40 Mhz bandwidth does not have a positive result. It is even recommended to reduce the performance of the transmitter.

I would only use 40Mhz bandwidth if the 20 and 40 Mhz performance tests show clear positives in the current conditions