Like Erwin allready pointed out, their is 2 types of connections with KPN Copper and Fiber
If you have Copper usually their is an small cable (RJ11) Telephone cable that comes from an Wall outlet and you need to put that cable on the Grey port that is called DSL.
If you got Fiber you most likely got an small box what they call NT or FTU with 3 Green lights ontop of that with names like Power Pon and Ethernet. from their can connect an cable into the Experiabox(modem) in the Red port which is called WAN.