If anyone still need this info.. I had to make quite some tests connecting UPS to my Mac, but they were succesfull :) To make this feature work you need to add additional option to config - allow_killpower = 1 [ugreenups] driver = usbhid-ups port = auto vendorid = 2b89 productid = ffff subdriver = Arduino desc = "Ugreen US3000 via USB" allow_killpower = 1 Also set Disable UPS Power after Shutdown: Yes Then in your NAS Bios set Power Failure Recovery: ON It will send shutdown.return command via NUT at the end of shutting down process. Then UPS will cut all power in 20sec (could be changed with NUT) and beep. When power is back - NAS will start normally.