无法通过 WAN 将客户端程序连接到服务器程序

Question

I have created a client server program on java language with serversocket and socket classes with datainputstream and dataoutputstream for sending and receiving data.

But the problem is that when I run it on LAN(local area network) or localhost it works properly but when I try to connect client with server over WAN (wide area network) it doesn't even connects to server

And to connect it over WAN I have entered ip address of server side program as parameter of socket class's contractor ex: socket s= new socket(ipadd,port); and it doesn't connects to server without any error or something

So please help me out I am stuck on this problem from a long time.

This is my server side program code

This is my client side program code

Answer 1

You are using your mobile phone to provide internet to your server(which is your laptop in your case), so here your mobile is acting as a router, and your mobile has provided local ip addresses to devices that connects to it. So what is happening is that when you enter your laptop's (server) ip address in client application for starting connection and your computer doesn't have any ip address in public(it has an ip address which is assigned by your mobile but it's not publically available and it's a local ip address which generally starts with 192.168........) so client app is unable to detect your server and servers which are connected to routers same is applied in their case.

So solution to this is, you enter your mobile's (which is providing internet to your server) ip address in your client application, and with any port forwarder application you do port forwarding to your server's(which is your laptop) ip address(and it's local ip address assigned by your phone/router to your laptop) and port(which you are using for communication with client), and there are many port forwader applications available on Google play store you can use anyone of them. So steps to start connection with client and server in your case are:

1: install and start any port forwader application in your phone from your mobiles store. 2: unable port forwarding (for every request which comes to your mobile's ip address) to your server's ip address (which is assigned by your mobile to your server). 3: Than enter your mobile's ip address in your client application.

And it will get connected to your server...