急急急！！TCPclient和server的连接超时。。。

写一个TCP协议的套接字编程的时候，和同学的电脑一起，他的做server，我的做client，在他那运行TCPServer.java,我这运行TCPClient.java，但是会出现这个问题：

this
Exception in thread "main" java.net.ConnectException: Connection timed out: connect
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(Unknown Source)
    at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at TCPClient.main(TCPClient.java:13)

//this是我在client运行的时候的输出

附代码：

TCPClient.java

import java.io.*;
import java.net.*;

public class TCPClient {
    public  static void main(String args[]) throws Exception{
       
        //Message from user
        String message;
        //Modified message from server
        String modifiedMessage;
       
        //创建客户机端的套接字对象，与服务器对应
        Socket clientSocket = new Socket("61.150.43.47",5678);
        //从用户键盘输入读取
        BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
            //创建了两个连接到套接字的流对象
            //outToServer为进城提供了到套接字的输出
            DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
            //为进程提供了来自套接字的输入
            BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
           
            message = inFromUser.readLine();
            //将从客户机读取的message+'\n'写入到outToServer
            outToServer.writeBytes(message + '\n');
            //当字符到达服务器时，流过inFromServer刘，并进入modifiedMessage字符串中，遇到回车结束。
            modifiedMessage = inFromServer.readLine();
           
            System.out.println("FROM SERVER:" + modifiedMessage);
        }

        //关闭套接字，TCP也被关闭
//        clientSocket.close();
       
   
}

TCPServer.java

import java.io.*;
import java.net.*;

public class TCPServer {
    public static void main(String args[]) throws Exception
    {
        String clientMessage;
        String capitalizedMessage;
        ServerSocket welcomeSocket = new ServerSocket(5678);
        while(true)
        {
            Socket connectionSocket = welcomeSocket.accept();
            BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
            DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
           
            clientMessage = inFromClient.readLine();
            capitalizedMessage = clientMessage.toUpperCase() +'\n';
            outToClient.writeBytes(capitalizedMessage);
            System.out.println((String)clientMessage);
        }
    }

}
//注：我之前在自己电脑上同时运行的时候是可以的，不会出现什么问题。。。