I use a 3G Modem to connect to the internet. When I connect this modem I can browse, can download anything from the internet and even use apt-get without any problem.
But the problem is somehow Network Manager can't understand that I have an active wireless network connection. For this reason I can't download anything from Ubuntu Software Center as it shows that I have no internet connection. Also I can't use VPN for this reason.
What's the problem?