Synology Cloud Station
The Synology Cloud Station keeps (user) selected folders synchronised between the client device and the server. The server is essentially the Cloud Station Server app on the NAS while the client devices are my mobile phones and computers. The Synology Cloud Station client app is available on Android, iOS, Windows and Macintosh.
Synchronisation direction can be defined for each synchronised folder-pair: two-way, upload only or download only.
The Cloud Station does versioning for synchronised files. This allows me to download/ restore previous version of the files. Restoring a previous copy of a file will replace the current copy.
The important folders (camera folder, documents folder, etc.) on my Android mobile devices are backed up using this method.
Other useful things to do with Cloud Station
Pruning old files off your devices
As my mobile phone does not have expandable storage (i.e. SD card), I made use of the two-way sync feature to prune older files. Basically, I just have to shift the older files on my NAS to an non-sychronised folder and the files will be removed from my mobile phone. This effectively prunes and free up storage capacity on my mobile device.
Remotely push files to devices
Similarly for my toddler’s video-cum-music-player (a ruggedised Samsung S4), I am using this method to remotely push down new contents to her phone. I just have to drop the new files into the synchronised folder on the NAS and they will be downloaded to her device. No more fighting with her over the control of the phone.