How do I set up 2.4g network in my 5g att internet wifi for home smart device

We're here to help with the instructions, @Bocaman41!

Thank you, Constructive for providing the perfect link to help out.

If you follow that link, there is another great option that was posted on how to change your Wi-Fi settings. You'll simply need to pick the type of AT&T Gateway you own, and decide if you want to change the information via your Gateway's configuration, or using Smart Home Manager. To seperate the network into 2.4g and 5g, you'll just need to make sure they have different names.

If you have any further questions, please let us know. Thank you for being a valuable part of AT&T!

Donovan, AT&T Community Specialist

Assign a separate SSID to the 2.4GHz band and then point your 2.4GHz devices to it.

Sorry, but I am not that user savy. I need more information or instructions. Can you point me to a site that would contain detailed instructions?

‎how do i separate the 2.4g from the 5g on my router | AT&T Community Forums (att.com)

A simple way to achieve this is to enable your Guest Wi-Fi, which is 2.4Ghz. You can then connect your devices to that SSID as needed.

Ummm how do you set up a "Guest Wi-Fi" do you have to log off main PC and on as a "Guest"?

No you login to your router google it for instructions 

Ok I tried I typed in exactly the following into the url and hit enter, it said the page doesn't exist or has been moved and gave me that nonsense page they send you to when you don't have a valid URL: http://att.wirelessinternet

To enable the Guest Wifi route, go to http://192.168.1.254/cgi-bin/wconfig_unified.ha , enter the Access Code found on the gateway's label and Enable the Guest SSID and then click the Save button.  Note the password as it's different for the Guest Network