A FRITZ!Box 4G or 5G router works with a SIM card via a mobile data connection. You don't have to connect these routers to fiber optics or a modem. This way, you can set up a WiFi network anywhere. Choose a 4G or 5G router if you're on the go often, don't have a fixed internet connection in your house, or want good and reliable WiFi on vacation. That's much safer and faster than connecting to a public hotel or library network, for example.