No. All models of Deeper smart sonars will work without any mobile or internet connection, so you don’t need to worry if the location you’re fishing has a mobile signal or not. You could be fishing in the Amazon rainforest and your Deeper smart sonar will still work. However, there are few functions on the app which require an internet connection, such as weather forecast and solunar calendar.
Deeper Start/PRO/PRO+ models themselves are fitted with a Wi-Fi connection which they use to transmit data to your phone or tablet, but this works independently of any networks. All you have to do is to turn on the Wi-Fi on your smartphone or tablet, and connect to the signal from your Deeper.