If the Source and Sink blocks are on two different computers on the same LAN, then the IP and port number of the Sink block must be specified on each end of that connection. For example, if the Sink is on IP 192.168.2.14:5678 and the Source is on IP 192.168.2.5, both Source and Sink blocks must specify the Sink IP and port (192.168.2.14:5678).