The Linksys RE6400 setup is the step-by-step process of installing and configuring the RE6400 Wi-Fi range extender to improve your existing wireless network. During setup, the extender is connected to your main router so it can capture the Wi-Fi signal and rebroadcast it to areas where the signal is weak or inconsistent. This helps eliminate dead zones and ensures a stronger, more reliable internet connection throughout your home or office.