Techniques are disclosed for transmitting a message to a user device in accordance with a determination that another device is unreachable over a network. In one example, a server device, at a first location, may identify a controller device resident at a second location, whereby the controller device is configured to communicate with a router at the second location. The server device may also receive a list of user devices. The server device may transmit a ping message to the controller device via the router to determine whether the controller device is unreachable by the server device. The server device may subsequently transmit a message to a user device on the list in accordance with a determination that the controller device is unreachable by the server device, whereby the message includes instructions for the user device to determine whether the controller device is unreachable by the user device.