Loss of internet connection

Hi,

I have a connection problem with my Vostro 1720.  Now I have to keep both physical and wireless connections on because from time to time, like right now, for no apparent reason I loose the wired connection.

At first, I thought it was the router, so I bypassed this device and connected the laptop directly into the modem. Still no internet connection, even after resetting the modem. I called the technical service of my internet supplier, I followed his instructions but we could not find the problem.

I then reconnected the router to the modem and I started my old desktop computer.  This wired internet connection worked perfectly but the one to my Vostro refused to work properly, so I activated the wireless connection and it worked without problem.

I would prefer to use the wired connection for security and speed reasons, so I would like this to work as it is supposed to.

Any clues?

Gilles Paquette