Here are my quick step to get all those devices working together.
First, Install the domotics package on your synology (from community repo).
Next, install the UsbSerialDrivers downloadable here: UsbSerialDrivers_3.0.6.spk
Follow the next step on this guide: http://www.vesternet.com/resources/application-notes/apnt-86#.VrknUpMrKAy
DI-O Switches, Dimmer and plugs uses the AC protocol.