After upgrading to Ubuntu 9.04 I've found the network manager GUI to be far superior to the previous version I was using in Ubuntu 8.04 LTS. Unfortunately when I was using Ubuntu 8.04 I made some custom alterations to my network setup in the "/etc/network/interfaces" file. The Network Manager in 9.04 wasn't keen on this and so refused to manage it, instead it displayed the message "Wired Network - device not managed".
As a work around I commented out all of my changes by placing a # at the beginning of each line in my interfaces file:
Open the interfaces file in an editor:
sudo vim /etc/network/interfaces
This is an example of how my file looked before I modified it. Yours will be different:
auto lo
iface lo inet loopback
iface eth2 inet static
address 192.168.0.44
netmask 255.255.255.0
gateway 192.168.0.1
auto eth2
And here's the same file again, but I've added #'s at the beginning of each line so that they are ignored:
#auto lo
#iface lo inet loopback
#iface eth2 inet static
#address 192.168.0.44
#netmask 255.255.255.0
#gateway 192.168.0.1
#auto eth2
In order for the changes to take effect, we need to restart the network manager and the applet by running each of these in the command line:
sudo /etc/init.d/networking restart
And now restart the network manager applet:
pkill nm-applet
nm-applet
You should now be able to manage the network connection from within the network manager applet.
Ubuntu 9.04 nm-applet