Make sure that you have sufficient WiFi signal where you are planning on mounting the heater. Remember that the WiFi signal range on the heater is lower than what you experience with for example cell phones. Make sure that the heater, phone and WiFi router are close to each other when installing.
Different building materials will influence the range of the WiFi router. The range of the WiFi signal is especially affected by what kind of material the house is built with (concrete, woodwork etc.)
If you experience a weak WiFi signal we recommend increasing the signal by using a WiFi range extender (repeater/extender) to make sure the heaters have a stabile signal.