Client-Server Program: Client can connect to server easily but server can't respond cause target machine actively refuses connections

See more:

C#

network

sockets

Hey,
I am trying to write a client-server program for the first time. It works fine on LAN networks but I can't get it to work over internet.

I can easily send data to the server program with the following code:

public static bool sendTo(IPEndPoint ip, String data)
{
    using (TcpClient c = new TcpClient())
    {
        try
        {
            c.Connect(ip);
            NetworkStream clientStream = c.GetStream();
            ASCIIEncoding encoder = new ASCIIEncoding();
            byte[] buffer = encoder.GetBytes(data);

            clientStream.Write(buffer, 0, buffer.Length);
            clientStream.Flush();
            c.Close();
        }
        catch
        {
            c.Close();
            return false;
        }
    }
    return true;
}

Then server has to respond to the client using the same code but it fails giving the following error:

No connection could be made because the target machine actively refused it *IP*:*PORT*


I know the problem can be fixed with port-forwarding and changing the settings of router. But I'll probably try to make a software out of this soon and users should be able to use the software with minimal configurations. So... I was wondering if anyone can help me here...

Thanks in advance,
eLe