WiFi: When and how to use WIFI_BW_HT40?

[vonnieda]

Hi all,

I have a customer that was unable to connect to WiFi because their AP was configured for 40 MHz channels. I see in the docs that I can call esp_wifi_set_bandwidth() with WIFI_BW_HT40 but in the docs there is a note that says "2. WIFI_BW_HT40 is supported only when the interface support 11N". So, this raises a few questions:

1. Does this refer to the interface on the ESP, or on the AP I am connecting to?
2. If the ESP, does it support 11N and thus this call should work?
3. Will setting this to WIFI_BW_HT40 restrict me from connecting to 20 MHz channels?
4. Any suggestions or best practices for this settings to be able to connect to as many AP configurations as possible?

For reference, I am using WIFI_MODE_STA.

Thanks,
Jason