Synology NAS (DS218+) and Full Disk Encryption (FileVault2)? I’m wondering, if there is a way to enable Whole Disk Encryption on a Synology NAS (in my case DS218+). 

Every topic regarding encryption on a Synology NAS addresses “Folder Encryption” rather than encrypting the whole disk. Since I am going to put all my personal stuff - including sensitive information - on the NAS to keep my Desktop and Laptop (Apple OS X) in sync, I need to encrypt it.

As I see it, the easiest way would be to encrypt the whole disk using Apples File Vault2. Is it possible or will I have to find another solution rather than using a (Synology) NAS?

Appreciate your help!
Every topic regarding encryption on a Synology NAS addresses “Folder
  Encryption” rather than encrypting the whole disk....As I see it, the easiest way would be to encrypt the whole disk using Apples File Vault2.


You can't use Apple's "whole disk" encryption on any NAS device because if you were actually able to, the NAS won't be able to access it.

When you are connecting to a NAS, you are mounting a shared volume (not a disk); even if that volume happens to spans the whole disk.  Synology's built in folder encryption is designed specifically to address this.