I spent several hours with discovering of this:
1. Each DSM contains a feature "Synology UPS server"
you can setup it by Control panel/Hardware & Power/UPS/Network UPS Type + Enable UPS Server
it can helps you to manage another NASes connected to your LAN as the Synology UPS server
If I set my NAS to shutdown, say between 11pm and 6am and then set the backup schedule to 2am to a connected USB HD, am I correct in assuming that the backup will wake the NAS; create the backup and then shutdown again?