Laptop Internet Port Not working?

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I had just recovered my laptop using the recovery system. Before I recover the laptop, the internet connection is working properly. I using the the internet cable which plug into my laptop internet port.(didnt use wifi because this is University's hostel service. It is free). Okay, after I recovered my laptop. I plug the cable into the port, initially I still connected to the network but after 5 minutes or sooner, I cannot get the connection.it shown connected on the local network connection window there,but the Explorer is just not respond to any website. I did tried connect to wifi, there is no problem with wifi connection, I can surf smoothly. What should I do?