Checking WiFi Bands
Method 1: Are there multiple options with your WiFi network's name?
Open up the WiFi settings on your computer or phone and see if there are multiple options, for example, Home WiFi 5GHz and Home WiFi or Home WiFi and Home WiFi 2GHz.
If so then you do have a 2GHz WiFi band
Method 2: Is there only one option with your WiFi network's name?
Which device are you using to check if your WiFi has a 2.4GHz band?
Android
Connect to your WiFi network
Go to Settings > Network & Internet > WiFi >
Read the Frequency settings, it will either be 2.4GHz or 5GHz
Windows
Connect to your WiFi network
Open your network panel from your taskbar
Go to Properties, then scroll down to the Properties section
Read Network Band, it will either be 2.4GHz or 5GHz
iOS
Connect to your WiFi network
Go to Settings > WiFi > Information
Read the
Mac OS
Connect to your WiFi network
Click on the WiFi icon in the top navigation bar while holding down the Option ⌥ key
Read the Channel information, it will either be 2.4GHz or 5GHz