RAX20 router 2.4 Ghz issues

I would like to get a solution to my problem. My router shows two wifis one is 2.4 Ghz one and the other is 5Ghz. The 5Ghz one works fine, I can connect to it with no problems. Unfortunetly that is not the case with my 2.4Ghz connection. It appears as an option to connect to but it keeps rapidly disconnecting whenever I try to use it. I still have some old devices that don't support 5Ghz. And I really need my 2.4Ghz band to work. The router is updated with the latest firmware. I just got my router few days ago so is pretty much still brand new. Any advice would be appreciated.