If your camera is online
1) The camera appears online in your camera list of the mobile app, AND
2) The LED light (on the back, front, or side of the camera depending on your model) is green
but you cannot start the live video stream, try one of these troubleshooting solutions:
Reduce the Resolution
1. Click on the gear icon next to your camera.
2. Under Video, turn off Auto Adjust.
3. Change the Resolution to anything lower than 1280x720.
3a. You can even try to lower the Frames per Second or Quality.
4. Start your live video stream again.
Connect to a Different Network
If the internet connection on your mobile device is poor, you may want to switch to a different network. You can switch to a different wireless router (if available) or turn off WiFi altogether and connect via 3G or LTE.