To ensure that the Linksys RE6400 setup is operating under maximum security after the installation, changing the password is vitally important. The previous default password is simple to guess, making it easier for unauthorized users to have access to the network. Therefore, to change passwords, first, set aside your web browser and type the router's default IP Address into the address bar and hit the Enter key. Immediately this is done; you will see the Linksys Extender login page on your screen. That is the setting, so you just open it. Just open the page and click password settings and then select the encryption option; finally, apply the new password.