Connected products communicate between each other by radio, and each of the wired products transmits the signal. It is not necessary to put the products close to the gateway power outlet / gateway module. Just ensure that there is no more than ~30 feet (10 meters) between two of your installation's wired "...with Netatmo" products.
The wireless switches can control products which are not directly within their range. Just ensure that the wireless switch is installed less than 30 feet (10 meters) from the closest "...with Netatmo" wired product. To ensure that the wireless switch is close to the installation, keep it in the desired location and test it works before securing it.