The Sleep Mode WOL functionality allows to entirely switch off the device, including the network interface, and to switch on again by using the standard WOL (Wake-on-LAN) mechanism. The transition to the Sleep Mode WOL state is initiated by invoking the SwitchOffWOL Method of the EnergyDevicePowerOffType.
If the switched off device contains the OPC UA server, the connection of the OPC client to the server disconnects. The server will be reachable again after a wake up of the device by Wake-on-LAN (sending the WOL magic wake-up packet).