The further you move away from a router, the worse reception will be. The transmission power may vary from router to router. This depends largely on the manufacturer and model.
The reception strength is indicated with the so-called RSSI value. The unit is dBm (decibel milliwatt). 0 dBm corresponds to 1 mW (milliwatt) power.
For GASTROFIX, an RSSI value of max. 60 dBm (without guests) recommended. The reason for this is that guests cause a "attenuation" of the signal, so that a maximum RSSI value of -70 dBm is generated.
If the WiFi reaches the above mentioned RSSI value, it is in the "operational" area for the GASTROFIX-App.