Valid wireless channels

The command iw phy0 channels returns a list of wifi channels. Under some it says Radar detection and or No IR. I was wondering what do both of these mean individually. Can I use channels which have these listed on them?

You'll only be able to use channels that don't have the "No IR" flag. So if they list a dBm or show "radar detection" you can use them. Make sure you set a regulatory domain to be allowed to use the radar detection channels.

The no-ir flag exists to allow regulatory domain definitions to disallow a device from initiating radiation of any kind
-- https://wireless.wiki.kernel.org/en/developers/regulatory/processing_rules

Thanks. Channels which show Radar detection don't work when I try to use them (the wifi device doesn't go up after restarting). Do you know why this is? Here is what the output of iw phy0 channels looks like for this channel:

* 5500 MHz [100] 
  Maximum TX power: 27.0 dBm
  Radar detection
  Channel widths: 20MHz HT40+ VHT80 VHT160
  DFS state: usable (for 291 sec)
  DFS CAC time: 60000 ms

You have to set your regulatory domain. Basically the country you are in.

Through the command line, edit /etc/config/wireless to include

option country 'DE'

or whatever is appropriate for your location.

Through LuCI go to Network -> Wireless -> Edit -> Advanced Settings and set a Country Code.

-- https://lede-project.org/docs/user-guide/wifi_configuration#dfsradar_detection

Thanks - that seems to have solve most of my problem. I've made another post here about the remaining one. Thanks for your help.