We have a 4 level house. The computer the greatest distant from the AirPort Extreme does not receive a very strong wireless signal. Our Extreme is the latest model - A1521. I'm wondering if I can use an AirPort Express WIRELESSLY to extend the network in the house? I believe the added on Express can be configured through the AirPort Utility app. So hope would be to just plug the new Express in to AC power and then configure it as a "second" router.