To add to @byackee1’s answer: when you pair your UPS / NAS / Switch Port, expand the section in which you can provide the IP address manually. There you enter the device’s IP address and also set the custom SNMP community string that you want to use. You need to configure the same community string on your NAS / Switch of course.
Just to be sure: If your NAS is accessible via the internet, make sure that you block the SNMP service in your NAS’s firewall and enable it only for local/LAN traffic.
