Heya. Many thanks for your interest in our network library and welcome to our forums. Please use the following syntax:

try
{
    IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
    IPEndPoint endPointToUse = new IPEndPoint(ipAddress, 12345);
    TCPConnection.StartListening(endPointToUse, false);
}
catch (CommsSetupShutdownException)
{
    Console.WriteLine("The requested port '12345' was already in use.");
}

Regards,
Marc