Centra is wired with high speed fibre optic internet cabling. It is 'FTTB' which stands for Fibre To The Building. 

Your unit is wired with Cat6 ethernet cabling. The connecting plug is located along side all TV points. This allows you to hardwire your internet from your modem direct to your TV, rather than rely on the modems WiFi connection. 

To do this, you only need buy a length of Cat6 ethernet cable that will reach between your modem and the ethernet wall socket that will be close by your NBN box.

You will also need a Cat6 ethernet cable to plug in between the wall socket and your TV/Computer. Once connected adjust the settings on your TV or computer to accept a hardwire connection...simples! 

NB: Cat6 cable is common and easy to find. Purchase from Bunnings, Jaycar, JB Hifi etc