We can help if you describe the specific device and method you're using to connect to your 2.4Ghz wireless networks. Some IoT devices have difficulty joining your wireless when the 2.4Ghz shares its SSID with 5Ghz, as Orbi does, but there are workarounds to get around this initial joining step and then the device works fine.
If you're trying to setup an IoT device and its app wants you join your phone to the 2.4Ghz wireless connection then that's not going to be easy. Sometimes these apps offer a secondary, more manual method for setting up the wireless and that works for wireless systems with a 2.4Ghz/5Ghz shared SSID.
