Synology Nas hardware failure, replace it by Rock PI 4

[Dante4]

I’m a bit late to party, but you can use just power RockPi with 12v from USB type-c port. That’s applies to both RockPi A and RockPi B and RockPi C, because they have the same PSU

Power supply for the rockpi

Should be possible. I think I’ve red it can be powered with dumb voltage up to 20V. Maybe with this you could do this. Wait until @jack or @Stephen agree to do this. I wouldn’t want you to burn up that beautiful board.

As for your whole project:
About sleep mode:

1. To make Wake-On-Lan you will need something like RockPi E or RasPi Zero as a gateway to turn everything back.
2. You can halt system and wakealarm, like - you manually or crontab halt system with inserting time when you need to start it back
   Does the rtc on rockpi4 support wakealarms - #3 by Stephen

Now about power supply. As was said before you can supply 12V directly to TypeC, but RockPi itself can’t supply 12V anywhere, so you will need to parallel connect it, aka:

PSU12v ---power>--- RockPi
 power|             |sata
      ->----HDD<---->