In principle, it does not matter with which router/modem you use the powerline. However, there must be a free (gigabit) Ethernet interface on the router/modem.
To use the PLA5456, one of the two devices in the starter kit must be connected to the modem or router using a LAN or Ehternet cable. The second Powerline from the starter kit is then plugged into the socket in the room where you want to connect the device to the network or the Internet via an Ethernet cable.
If you have any further questions about the possible applications, please do not hesitate to contact us at digitec@zyxel.ch.