Most (actually almost all) IoT systems are not well-thought-out in this regard. It requires a bit of paranoiac foresight. Designers far too often think it's really, really important that remote devices stay connected to the mothership, when in reality, most IoT devices would be far better off NEVER requiring a cloud connection, but leveraging one if/when available.

*Rule One of IoT network design: NEVER assume that you even have a network * If at all possible, and to the maximum degree possible, an IoT device must work whether there's a network available or not.