What is the difference between a KNX IP Interface and a KNX IP Router?
A KNX IP Interface allow you to program and connect to the KNX bus over IP. It supports direct tunnelling connections and most IP Interfaces support multiple simultaneous connections.
A KNX IP Router also allows you to program and connect to the bus but can be used to connect different parts of a KNX system together over IP. It does this using an additional multicast connection and manages the KNX traffic using a filter table in the same way a line coupler does. The Multicast connection can also be used as a bus interface for programming and external devices.
Third party systems will connect to KNX with either a tunnelling or a Multicast connection. Because of this we generally recommend a KNX IP Router as it has both options, ensuring compatibility.