Losing connection is usually a result of a loss of reception, older or less robust technology (e.g. cheaper phones) or even from mobile service providers (e.g. Vodafone, Optus or Telstra).
If you see the error message, "You have lost connection", the app will attempt to reconnect to the server automatically and continuously.
Do not attempt to force close the app to try to get it to reconnect. It will continue to reconnect every 30 seconds and data will be retained over this period for your photos, GPS tracking and job updates.