Cable Modem Router 2.4ghz Not Working but 5.0 is

Main router with 2.4ghz isn’t being detected by any of my devices. I have reset the router, rebooted, restored to factory default settings, tested my modem and internet provider. All is working fine but the router will show no internet for 2.4ghz. I have several devices that will only work with 2.4ghz and I am very frustrated. I have tried to backdate the firmware (currently using v. 1.0.1.20) to an earlier version but the web service automatically updates the firmware back to version 20. The netgear genie app doesn’t even display a router update option so I don’t know what else to do.

Is there a solution to this problem? I have not been able to find one that works from the netgear community.
Please, help as soon as possible!