I have a Synology DS1821 with a UPS connected by USB. I also have other devices on my network that are connected to that UPS so that they remain active during a power outage. What is the best way for me to safely shut down the other devices in the event of an outage? I have read so many options that it's a little overwhelming. They mentioned networkmonitortools, apcupsd, nuts - I'm just not sure.

I have multiple docker containers running on my synology so i'm open to any containerised solutions too.

I have OPNsense running as my router. I have a TP-Link Omada switch. I have a Windows desktop running my CCTV software. I would like them to shut down cleanly in the event of an ongoing outage that has lasted longer than X minutes.

What are my options?