To achieve an ideal coverage we recommend to mount the transmitter centrally to the devices you want to control.
To leave the transmitter as much space as possible.
Avoid metal objects / transformers / or other electrical devices in the immediate vicinity of the transmitter.
On the following picture you can see the propagation of the radio waves with decentralized installation.
The propagation is severely restricted by the building structure and the installation location.
The next picture shows an assembly in a central position.
The propagation of the radio signal is much better than with a decentralized installation.
Influences such as walls, walls with metal braces, electrical cables and other electrical devices can influence the range.
If radio networks are within range, they can also influence the range.
In the following figure you can see the attenuation of the signal by different materials, e.g. a concrete wall can reduce the signal quality by 80%: