No internet connection after upgrade to WIN 8.1

Dear all,

I have a serious problem. I upgrade my Laptop (DELL Inspiron 3521) from Windows 8 to Windows 8.1. The upgrade finished and all seemed to work fine but when I went in Desktop Mode I noticed that I cannot open web pages from all browsers (IE, Mozilla, Chrome). Also I noticed that some programs when I press to check for updates they are saying that there is no connection to the internet or check the firewall.

I search the internet and I found that maybe the problem is the antivirus, so I completely uninstall the ESET but with no result.

I have to say that in METRO Mode the internet is working fine.

Please give me a solution the soonest possible.

Thanks in advance

Elias Kekakos