@vandeo 

WPS function will help you add a new device to the network quickly. If the new device supports Wi-Fi Protected Setup and is equipped with a configuration button, you can add it to the network by pressing its own configuration button and then press the button on this device within two minutes. The status LED on this device will light green for five minutes if the new device has been successfully added to the network. If the new device supports Wi-Fi Protected Setup and the connection way using PIN, you can add it to the network by entering this device's PIN.

• WPS Status - Enable or disable the WPS function here.
• Current PIN - The current value of this device's PIN displayed here. The default value can be found in the label or User Guide.
• Restore PIN - Restore the PIN of this device to its default.
• Gen New PIN - Click this button, and then you can get a new random value for this device's PIN. You can ensure the network security by generating a new PIN.
• Disable PIN of this device - WPS external registrar of entering this device's PIN can be disabled or enabled manually. If this device receives multiple failed attempts to authenticate an external registrar, this function will be disabled automatically.
• Add Device - You can add the new device to the existing network manually by clicking this button.

You can look at this thread for an example - use a computer to be sure tha the printer is discoverable and then try with your mobile.