App disconnecting during cooking?

My wife’s iPhone 6 keeps getting disconnected from the app and the timer when she’s cooking. What can we do to fix this? Our WI-FI is fine on all other devices.

The App is Bluetooth not WiFi. Bluetooth has a extremely short range compared to WiFi and disconnects very easily as the distance increases between the unit and her phone. I tried it and I found that with my trips to the outside and basement staying connected was spotty.