@Lazaruz Just to clarify, the NVR is plugged into a UPS? Or is it plugged into the outlet, and then you have a backup generator that kicks in that can start the VIGI NVR?

If the latter, I recommend you get a UPS so you can safely shut down the NVR, especially if the power goes out frequently. 

  @Lazaruz A UPS is designed to only have enough power to allow you to safely shut down the devices behind it, if it regularly runs out of energy it's not really doing its job, and you likely need a backup generator instead. 

  @Lazaruz If possible I'd try to solve your power issues first to prevent your building power from going down so frequently. As far as i can tell, if powering off the NVR normally does not cause the issue, you should be looking to solve the power issues here first.