@Amir.limx 

So do you mean that you need disconnect and reconnect the devices which support 2.4GHz only manually to connect to the nearest Deco manually, it won't switch to the Deco with better signal automatically? 

First, cause it does not support 5GHz, it won't switch to the 5GHz automatically which has better signal strength and faster speed than 2.4GHz to some extent; then if the signal strength with the original Deco does not reach the threshold value, it won't trigger the AP steering feature. 

The Deco app does not support the feature to fix the specific Deco your devices connect to, while we have noted that and inform our product engineer. They will work on it later. 

Good day. 

@Amir.limx 

Hello, try to move the 2 Decos further away from each other first, and then connect the certain device to the second Deco and disable mesh technology on the Deco app, and you can relocate the Deco.

After that, please verify whether the device will connect to the nearest Deco.

May it help and have a nice day.