Using a WiFi extender to connect 2.4ghz devices

Due to the fact that Orbi doesn’t allow you to separate 2.4 and 5ghz, I’m having issues connecting certain smart home devices. I’ve tried the walk far away method, and it has not been working. What are the chances that you can use a Wi-Fi extender (or some sort of 5ghz to 2.4 converter) to connect to the devices or use a similar device to change the same network name in order for them to work.

I’m not sure if I’m making any sense. Let me know and I can rephrase.

My device: Orbi CBR750