我想分享我发现的这个答案，因为问题的原因不是防火墙或进程没有正确侦听，而是我使用的微软提供的代码示例。

https://msdn.microsoft.com/en-us/library/system.net.sockets.socket%28v=vs.110%29.aspx

我几乎完全按照所写的那样实现了这个函数，但发生的事情是我得到了这个错误:

2016-01-05 12:00:48075 [10] ERROR -错误是:System.Net.Sockets.SocketException (0x80004005): No connection could be made because The target machine actively refused it [fe80::caa:745:a1da:e6f1%11]:4080

这段代码将表示套接字已连接，但不是在正确通信实际所需的正确IP地址下。(微软提供)

private static Socket ConnectSocket(string server, int port)
    {
        Socket s = null;
        IPHostEntry hostEntry = null;

        // Get host related information.
        hostEntry = Dns.GetHostEntry(server);

        // Loop through the AddressList to obtain the supported AddressFamily. This is to avoid
        // an exception that occurs when the host IP Address is not compatible with the address family
        // (typical in the IPv6 case).
        foreach(IPAddress address in hostEntry.AddressList)
        {
            IPEndPoint ipe = new IPEndPoint(address, port);
            Socket tempSocket = 
                new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);

            tempSocket.Connect(ipe);

            if(tempSocket.Connected)
            {
                s = tempSocket;
                break;
            }
            else
            {
                continue;
            }
        }
        return s;
    }

我重写了代码，只使用它找到的第一个有效IP。我只关心使用IPV4，但它与localhost, 127.0.0.1，和您的网卡的实际IP地址，其中微软提供的例子失败了!

    private Socket ConnectSocket(string server, int port)
    {
        Socket s = null;

        try
        {
            // Get host related information.
            IPAddress[] ips;
            ips = Dns.GetHostAddresses(server);

            Socket tempSocket = null;
            IPEndPoint ipe = null;

            ipe = new IPEndPoint((IPAddress)ips.GetValue(0), port);
            tempSocket = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);

            Platform.Log(LogLevel.Info, "Attempting socket connection to " + ips.GetValue(0).ToString() + " on port " + port.ToString());
            tempSocket.Connect(ipe);

            if (tempSocket.Connected)
            {
                s = tempSocket;
                s.SendTimeout = Coordinate.HL7SendTimeout;
                s.ReceiveTimeout = Coordinate.HL7ReceiveTimeout;
            }
            else
            {
                return null;
            }

            return s;
        }
        catch (Exception e)
        {
            Platform.Log(LogLevel.Error, "Error creating socket connection to " + server + " on port " + port.ToString());
            Platform.Log(LogLevel.Error, "The error is: " + e.ToString());
            if (g_NoOutputForThreading == false)
                rtbResponse.AppendText("Error creating socket connection to " + server + " on port " + port.ToString());
            return null;
        }
    }

I was facing this issue today. Mine was Asp.Net Core API and it uses Postgresql as the database. We have configured this database as a Docker container. So the first step I did was to check whether I am able to access the database or not. To do that I searched for PgAdmin in the start as I have configured the same. Clicking on the resulted application will redirect you to the http://127.0.0.1:23722/browser/. There you can try access your database on the left menu. For me I was getting an error as in the below image.

输入密码，并尝试是否能够访问它。对我来说，这行不通。因为它是一个Docker容器，我决定重新启动我的Docker桌面，右键单击任务栏中的Docker图标，然后单击重新启动。

在重新启动Docker后，我能够登录并看到数据库，并且当我在Visual Studio中重新启动应用程序时，错误也消失了。

希望能有所帮助。

这是非常具体的，但是如果你在尝试使用mongo连接到数据库后收到这个错误，对我来说，在运行mongo.exe之前运行mongo.exe，然后连接工作正常。希望这能帮助到一些人。

我现在就面对这个问题……

在我这边，我有2个独立的Visual Studio解决方案(.sln)…在各自的Visual Studio实例中打开每个实例。

解决方案2调用解决方案1代码。问题与分配给解决方案1的端口有关。我不得不将解决方案1上的端口更改为另一个端口，然后解决方案2又开始工作了。因此，请确保检查分配给项目的端口。

最可能的原因是防火墙。

这篇文章包含了一组可能对您有用的原因。

从文章来看，可能的原因有:

FTP服务器设置 软件/个人防火墙设置 多种软件/个人防火墙 杀毒软件 LSP层 路由器固件 关闭电脑 电脑未插电 提琴手

这可能是因为授权问题;我就是这样。 例如，如果在控制器函数的顶部有[Authorize("WriteAccess")]或[Authorize("ReadAccess")]，请尝试将它们注释掉。