If your Dedicated Server goes down for any reason and does not come back up with in 15 minutes, you can log into Unity to reboot the server.
First, log into Unity:
https://unity.serverintellect.com/
From there, select "My Services" -> "My Server"
Click "Reboot"
You will then have the option to "Soft Reboot", "Hard Reboot", "Power Off", and "Power On". We highly recommend starting with a Soft Reboot, waiting 15 minutes, then trying a Hard Reboot. If your server does not come back on with in 10 minutes, please contact us right away: http://www.serverintellect.com/contact/
If you have a Virtual Server, please visit us at the link above the moment your server reports offline.