There are certain network setups where you may need to setup separate SSIDs for the 5GHz and 2.4GHz so all your devices can connect. This can be done by connecting to the Web GUI.
Navigate to the Network section and select either wireless (2.4 GHz) or Wireless (5 GHz). Select the one that corresponds to the band that you would like the new SSID to be on. In the image below 2.4 GHz is selected.
Select an SSID that is not currently enabled. In the image above SSID3 is selected.
Change the name of the SSID to be something that you will recognize and then select enable.
Once you click SAVE the changes will be applied to your network. Use your device to find the new SSID you just created.