Fri Jan 13, 2023 7:53 pm
In capsman channel width is controlled with channel property extension-channel. If it's set to disabled, then radio will be provisioned to 20MHz only channel, even if band is N or AC. If that's set to anything else, then channel width will be appropriately wide. E.g. if setting is extension-channel=XX, then radio will be provisioned for 40MHz channel width (20+20). Likewise if extension-channel=XXXX, radio will be provisioned to 80MHz channel width (4*20MHz).
Basically channel is constructed of one Control channel and zero, one or more Extension channels. Pre-N devices support only 20MHz channels and will only see/use Control channel. If you limit AP to only older standard, then it'll only emit Control channel obviously. It's benefitial to use N standard on 20MHz-only channels due to support for MIMO (multi-chain) which improves throughput without using wider frequency channels.
If you want to control extension channels kayout, configure it explicitly - e.g. instead of configuring it to XXXX, use eCee.
In mikrotik world, when you set frequency, this means Control channel centre frequency. Depending on channel layout wider channels will be centered at lower or higher frequency (never centered because wide channels never use odd number of 20MHz channels).