From Xojo Documentation
Specifies which network interface the socket should use when binding.
Leaving this property set to Nil will use the currently selected interface. In the case of UDPSockets, if you assign a non-Nil value, the socket may not be able to receive broadcast messages. The behavior is OS-dependent; it appears to work on Windows but not on other supported operating systems. If you wish to send broadcast packets out, then you should not bind to a specific interface because the behavior is undefined.
This example specifies that the TCPSocket will use the first Network Interface on the user’s computer.