In the SYSTEM page of the P3 there is a LAN button. Click it to open the settings page for it. There you will find all information related to the P3's network connection.

1. Follow the instructions for setting up your extender.
2. Connect the LAN cable to the P3 and extender.
3. After the extender is setup, it should give the P3 an IP address which will be viewable in the network page. With this information, you can create a new connection in the app for it.

If all goes well, you should see an IP address automatically filled in the Current IP address section of the SYSTEM page.

Take this IP address and open the GHL Connect app.
1. Press Add device, choose the P3
2. In the Host/IP section, type-in the P3's IP address which you saw earlier
3. Give this connection a name and press DONE

As long as the phone is connected to the same Wi-Fi network, you should be able to access your controller through the app.