I installed Ubuntu Server 12.04 on an IBM machine which has a Broadcom NetXtreme BCM5721 Gigabit Ethernet PCI Express card. I was able to connect to the Internet during and after the installation. I installed ubuntu-desktop to provide a GUI to manage the server. After installing the DE, I changed the settings of eth0 in /etc/network/interfaces file to static (from dhcp). I re-started the machine. Now, all the machines connected to the internal LAN can connect to this server and vice versa. But this server machine is unable to connect to the internet.
On clicking on the Network Manager icon on the top panel, it says that the Broadcom device is "not managed". Clicking on "Connection Information" shows "No active connections".
So, the server is accessible via the internal LAN but the server is not able to connect to the Internet. Can anyone help regarding this problem?