1. Try another Wi-Fi network.
2. Check if your time zone is accurate. Go to Settings > System > Date and Time.
3. Clear cache by going to Settings > Apps > See All Apps > "App Name" > Clear Cache.

For Capsule 3, Capsule 3 Laser GTV, Capsule Air and Mars 3 Air, Reset by going to Settings>System>About>Reset>Factory Reset
For Capsule 3 Laser ATV, Reset by going to Settings > Device Preferences > About > Factory reset.

If the above solutions cannot solve your issue, please contact Nebula Customer Support at support@seenebula.com for further assistance.