Using macOS

1. Connect to your WiFi network. 
2. Hold down the ⌥ Option key and click on the WiFi icon. A new window will pop up.
3. Navigate to the Channel information. The text will say 5 GHz or 2.4 GHz. 
   

   

    

Using Windows

1. Connect to your WiFi network. 
2. Press the Windows Key + I simultaneously.
3. Click Network & Internet.
4. Select "Wi-Fi" from the left menu (if applicable), then click on the link that says "Hardware properties" or "Properties" for your active Wi-Fi connection.
5. Scroll down the list of properties until you find the field labeled "Network band" or “Radio type”:
   • If you see 802.11n, 802.11g, or 802.11b, you are likely connected to 2.4 GHz.
   • If you see 802.11ac or 802.11a, you are likely connected to 5 GHz.
   • Some Windows versions will explicitly state "2.4 GHz" or "5 GHz."
      

Verifying the WiFi network frequency on your phone

Using iOs

According to Apple's instructions, you are required to install a 'Wi-Fi analyzer' app from the App Store.

Using Android 

You can check the Wi-Fi frequency (2.4 GHz or 5 GHz) your Android device is connected to using the built-in system settings, though the exact labels may vary slightly between different Android versions and manufacturers (like Samsung, Google Pixel, etc.).

Since Android does not display the frequency in a standard Wi-Fi details screen, the most common method is to use a third-party app.