How to Set Up UPS Auto-Shutdown on a Synology or QNAP NAS

Buying a UPS for your NAS is only half the job. The other half is teaching the NAS to shut down cleanly when the battery runs low, instead of freezing mid-write when the wall power dies.

This walkthrough covers Synology DSM and QNAP QTS over USB, then the NUT-style network share so one UPS can protect a NAS and a PC together. It builds on the buying advice in Best UPS Battery Backups for a Home NAS and Network Gear.

What you need before you touch settings

You need a UPS with a HID-compliant USB port, the USB cable that came in the box, and a NAS that can draw power from a battery-backed outlet. Keep the modem and primary switch on battery outlets too if you want the NAS to finish uploads before it powers off.

For a lighter single-NAS shelf, the smaller pure-sine sibling still exposes the same USB path:

APC towers remain common in mixed offices. They work for many Synology USB setups, with the caveat that simulated sine wave can annoy some Active PFC supplies:

Synology DSM: USB UPS auto-shutdown

1. Power the NAS from a battery-backed outlet on the UPS.
2. Connect the UPS USB cable to any USB port on the Synology.
3. In DSM, open Control Panel → Hardware & Power → UPS.
4. Enable UPS support, choose USB UPS, and Apply.
5. Set shutdown behavior. For a NAS that shares the UPS with a router, pick a fixed time such as 5 minutes or 10 minutes instead of waiting until low battery. That leaves reserve for the network gear.
6. Optionally enable Network UPS Server so another DiskStation or a NUT client can follow the same signal.

QNAP QTS: USB UPS auto-shutdown

1. Power the QNAP from a battery-backed outlet and attach the UPS USB cable.
2. Open Control Panel → System → External Device → UPS.
3. Enable the UPS, confirm the USB device is detected, and choose whether to shut down on low battery or after a set time on battery.
4. Apply, then run a short pull-the-plug test during a maintenance window so you can watch the event log.

QNAP wording varies slightly by QTS version, but the pattern is the same: detect USB UPS, set a shutdown threshold, confirm with a controlled outage test.

Share one UPS with a PC using Synology as NUT primary

When a desktop or Linux box shares the same UPS, make the NAS the USB primary and let the PC be a network client.

1. On Synology, enable Network UPS Server under the UPS tab and add the client IP under permitted devices.
2. On the client, install Network UPS Tools (NUT) and point upsmon at the Synology as a netclient / secondary.
3. Keep the primary (the NAS) scheduled to stay up longer than the secondary, or the client loses its signal mid-shutdown.
4. Test by cutting wall power: the PC should begin shutdown first, then the NAS, while the UPS LCD shows falling runtime.

This is the same NUT model Synology documents for DiskStation-to-DiskStation sharing. A PC just becomes another permitted client.

Safe thresholds that actually protect disks

• Short blips (under a minute): let AVR and the battery ride through; do not shut down.
• Outages you expect to last: shut the NAS down after a few minutes so journaled filesystems unmount cleanly.
• Low-battery wait: fine for a NAS alone on the UPS; risky when a switch and modem also need the last minutes of runtime.

After any real outage, check DSM or QTS logs for UPS events, confirm volumes remounted cleanly, and glance at the UPS LCD for replace-battery warnings.

Mistakes to avoid

Bottom line

Wire USB first, enable UPS support in the NAS UI, pick a timed shutdown that leaves reserve for your network stack, and only then layer NUT sharing for a PC. Start with a pure-sine HID unit such as theCyberPower CP1500PFCLCD or the smallerCP850PFCLCD if your watt budget is light. Pair that with a real 3-2-1 backup plan so a clean shutdown is not your only safety net.