Kann ich ein Daten-/Routerkabel verwenden, um meinen Fernseher mit dem Internet zu verbinden?

I’m not gerrman, but these outlets and descriptions suggest that the only way you’d get internet is by signing with a Cable internet provider. Then they’ll issue you a cable modem to connect to this port. Then you can put it on router mode and connect a WiFi router into it.

A workaround might be a „mesh-router“.
You can buy several satellites and connect to those via ethernet but such systems can be pricey.
Not to be confused with an extender. To my knowledge those form a different network and devices tend to want to stay connected to the network, they are already connected to (i.e. they are really annoying)