[RESOLVED] VB.Net TCPClient Connection Error 10049

[Nienna]

Hey,

I'm trying to make a server/client application that uses a TcpListener on the server-side which listens on my WAN IP (using IPAddress.Any method) and port 3000, and a TcpClient on the client-side, which connects to the server using a tcpClient.Connect(ipString, portNo), but this blocks for a number of seconds, after which it throws the error:

A connection attempt failed because the connected party did not respond properly after a period of time, or established connection failed because connected host has failed to respond.

A few points:

- I have checked, using the VS debugger, that IPAddress.Any definitely uses my WAN IP.
- When the TcpListener is not listening (ie. inactive), the same error is thrown by the client.
- I am running the server on my home computer and am using a router.
- I have tried configuring the DMZ setting of my router to allow access to my computer.
- I have also attempted to set up port-forwarding, but I don't know if I've done this correctly.

My code, if you need it:

Server

Dim port As Int32 = 3000
Dim server As TcpListener
Dim aClient As TcpClient

        Try
          server = New TcpListener(IPAddress.Any, port)
        Catch ex As Exception
            MsgBox("Could not initialise server: " & ex.Message)
        End Try

        Try
            server.Start()
            lblStatus.Text = "Waiting for connections..."
        Catch ex As Exception
            MsgBox("Could not start server: " & ex.Message)
        End Try

If server.Pending Then
            Try
                aClient = server.AcceptTcpClient()
            Catch ex As Exception
                MsgBox("Could not accept connections: " & ex.Message)
                Exit Sub
            End Try

Client

Dim client As New TcpClient
         Try
            client.Connect("82.**.***.170", 3000)
            Catch ex As SocketException
            MsgBox(ex.ToString, MsgBoxStyle.OkOnly, "Server Connection Error")
                Exit Sub
         End Try

[Atheist]

Is the client running on the same LAN? If it is, you could try connecting to the local IP instead of the external.
If that doesnt change anything, try a much using a much larger port number on both applications...like 40332.

Edit: By the way, is that the actual server code? Or a simplified "version" of it?

[Nienna]

That is the actual code. The program work when I connect the client to "localhost", but as this is going to be a distributed program, I need to be able to connect from different computers/IP's.

And yes, that is the actual code.

I tried the higher port number, but no luck.

Another point: I used http://www.canyouseeme.org/ to check whether these ports were open, and got a negative.

[Atheist]

If it works when you use Localhost, then it must be a router firewall issue. When you're using the external IP, it sends the data outside the local network, going through the router.

[Nienna]

Fixed this!

The problem was that TcpListener can't listen on an external (or WAN) IP. For anyone else who has this problem (with a router):

You need to

1. Have your tcpListener listen on your computer's local IP, and a specified port.
2. Set up your router to forward incoming requests for that port to your computers IP.
3. Have your TcpClient or Socket connect to your WAN IP, and the same port number.

[Eduardo123456789]

Fixed this!

The problem was that TcpListener can't listen on an external (or WAN) IP. For anyone else who has this problem (with a router):

You need to

1. Have your tcpListener listen on your computer's local IP, and a specified port.
2. Set up your router to forward incoming requests for that port to your computers IP.
3. Have your TcpClient or Socket connect to your WAN IP, and the same port number.

I know this post is old already, but I'm currently going through the same problem, I followed this tip to try to resolve, but without success so far. I was wondering if anyone had any success with this tip.

Waiting for answer...