Some Alarm.com cameras uses a POE to WiFi bridge to connect to the local network, rather than a direct ethernet connection. If the camera goes offline, it is possible the bridge is the cause and rebooting it should reconnect it to the local WiFi network.
1. Locate the bridge for each camera and check the LEDs (see image below).
2. The Power LED should be solid green. The Wi-Fi and Communication LED might not be lit up (attached article explains what LED mean).
3. Unplug both bridge from their power outlet until the Power LED goes off.
4. Then plug back in and wait. Eventually, the Power should go solid green again, the Wi-Fi LED solid white, and the Communication LED solid green.

If this does not reconnect the bridge/camera to local WiFi, contact the support desk for further troubleshooting.