Fix Forced Shutdown, Online (FSD OL) Stuck in NUT with Synology NAS

I’m running an APC Back-UPS 1100 battery backup that is connected via USB to a Synology NAS (DS918+) running DSM 7.2.x with UPS support enabled along with the network UPS server. This ensures that my NAS will safely shut down during a power outage if the UPS battery gets low, and it also allows other devices to see the power status of the UPS and take appropriate action as-needed.

I configured the Network UPS Tools (NUT) integration for my Home Assistant instance so it can see the status of the UPS. I even have a conditional card on my Home Assistant dashboard that will display its status if the UPS is not online/charging. This allowed me to create an automation that triggers when the battery is getting low during a power outage and then safely shuts down my Scrypted NVR server (it runs on Proxmox and I configured the Proxmox VE integration for Home Assistant). Then the automation will shut Home Assistant down.

This worked as expected the last time we had a power outage for a couple of hours. I have my hardware configured to turn back on when power is restored, and everything came back up on its own when our electric utility fixed the problem later that day. However, recently our power flickered for just a split second, and since then the NUT Status sensor in Home Assistant has been showing as “Forced Shutdown, Online” (or “FSD OL” in the Status data sensor), even though the UPS is fully charged and online.

To fix this, I disabled UPS support in DSM, applied the change, waited about 30 seconds, then re-enabled UPS support in DSM and applied the change. I waited another 30 seconds or so, then reloaded the NUT integration in Home Assistant. Now the status sensors are showing that the UPS is “Online” and “OL” as expected.