How to Find the Best Wi-Fi Channel for Your Router

Try to find which channel is less used and change to that channel on your router will improve connection signal quality

windows: download wifiinfoview http://www.nirsoft.net/utils/wifi_information_view.html
unzip and run the exe, it will show all detected SSID and their channels used together with other info.
your SSID in use is high lighted in green

Mac: Wireless Diagnostics
MacOS has this feature built in. hold the Option key and click the Wi-Fi icon on the menu bar at the top of your screen. Select “Open Wireless Diagnostics.”
Ignore the wizard that appears. but click the Window menu and select Utilities.
Select the Wi-Fi Scan tab and click Scan Now.
The “Best 2.4 GHz Channels” and “Best 5 GHz” Channels” fields will recommend the ideal Wi-Fi channels you should be using on your router.

Linux: The iwlist Command
Open a Terminal and run the following command:
sudo iwlist wlan0 scan | grep \(Channel

Android: Wifi Analyzer (app) How to Change Your Router’s Wi-Fi Channel
login to your router in web browser, find WiFi settings /WiFi admin or the like, change the channel from the menu and save.