Currently Being ModeratedFeb 27, 2013 12:25 PM (in response to bona18parte22)
I would try to connect directly from your modem to your computer, without using your router, if the problem persist there may be an issue with your internet service. See with your Internet provider.
Currently Being ModeratedFeb 27, 2013 12:38 PM (in response to bona18parte22)
Try creating a New Location.
Apple Menu / System Preferences / Network / Location : Edit Locations.
click on the + sign and call the new one anything you want. Let the Mac complete the job.