[Zxian]

Have you had this notebook for a long time? or is this an "all-of-a-sudden" occurrence?

If the notebook is new, it could be that the wired network card is fried. If it's all of a sudden... it could also be that it's fried. Try the ping suggestion and see what the results are.

Just a general note on ethernet that's not widely known. It's not always the greatest thing for your hardware to connect and disconnect ethernet cards/routers while they're still powered. You should power down at least one of the devices before you plug-in/unplug the cord. I've seen two cards and a hub go because of this.

Hope this helps.