After you have connected your tablet or computer to your modem with an Ethernet cable or via Wi-Fi, follow the instructions to access the interface of your FRITZ!Box:
Open a web browser
Enter "fritz.box" or "192.168.178.1" in the browser address bar
The FRITZ!Box user interface will appear. Log in using the administrator password.
You will then be able to manage the various features of your FRITZ!Box.
Watch the video below to change your password or the name of your Wi-Fi network: