Rungwell Tasks keeps up to four hours of work on your device for when the connection drops. While you are offline, a grey bar at the top of the screen says so, and new tasks are not downloaded.
When the connection returns, your completed items are sent automatically, oldest first. Do not sign out while items are waiting to be sent.
Some projects do not allow offline work, because the client does not allow its data to be kept on a device. Their task cards say Online only.