By default the Eedomus assign the usage of the Smart Plug as Light. Trying to switch On or Off the device will result not working. This is because the gateway uses the multichannel encapsulated command for the On and Off in this usage type (Light). The multichannel (MC) command for the Smart Plug is not the correct one. To solve this you must set the BASIC_SET command.

You have to go in the device configuration
Set the device usage as Electric Device.

Click on Save.

Once you will set this the command sent to the device will be BASIC_SET (On or Off) and in this case the device On - Off function will work properly.