I spent several days, as many of you have, attempting to connect a few of my 2.4Ghz devices to my TP-Link On hub that works on Google Home. This became a very frustrating process because the WIFI router prefers 5Ghz as you know.
Through much reading and many video's it seems the only way to get your phone to connect to 2.4Ghz was to walk a fare distance away from your home. I being a tech thought there had to be an easier way. I went to my pantry and pulled out some aluminum foil and put it over my phone, just so I could see the phone and use it. To my surprise this worked. My phone switched to 2.4Ghz and so I got my switch blinking red and Tuya Smart app searching and it connected.
I had to be about 15 feet away from my router for the aluminum foil to work, but I didn't need to leave the house. After getting it to 2.4Ghz you have about 16 seconds before it will turn back to 5Ghz. I just kept the aluminum foil on either way. On an android phone, you can go to your WIFI connection settings and see what frequency your on.
Best of luck
I don't know if this will help but many times I'm setting up a 2.4 GHz device and my phone when it disconnects from the device and reconnects to Wi-Fi it automatically goes to 5 GHz Wi-Fi so to prevent this during device setup I just disable auto reconnect for the 5 GHz hotspot that way it only reconnects my phone and the device I'm sending up to the 2.4 GHz which is where it should be. Occasionally you will find a device that even though it says 2.4 GHz only it will find the 2.4 GHz even if your phone reconnects it trying to go to the 5 gigahertz but that's rare I've seen that. Usually, disabling auto reconnect prevents that problem and if you want to connect to it automatically you'll have to re-enable it in your phone.
Half of my 2.4GHz devices actually connects when it says 5GHz. I've never seen my phone go to 2.4 unless I used the aluminum foil. I have several bulbs and fan switch where I've spent hours that never connected until I used the Aluminum foil which caused my phone to switch to 2.4. I'll see if I can try what you have suggested.
Just wanted to hop in here to see if we still needed help on this. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.
Have a great day.