Unmanaged network icon - Network manangement disabled
I find this happens after a bad shutdown. Just change
managed=false
to
managed=true
in /etc/NetworkManager/nm-system-settings.conf
Note: In newer versions of Ubuntu, the file is at /etc/NetworkManager/NetworkManager.conf
This worked for Ubuntu 17.04
sudo touch /etc/NetworkManager/conf.d/10-globally-managed-devices.conf
sudo service network-manager restart
You should look at the contents of the file /var/lib/NetworkManager/NetworkManager.state.
It should look something like this:
[main]
NetworkingEnabled=true
WirelessEnabled=true
WWANEnabled=true
Change any from 'false' to 'true' to re-enable networking. It may work better if you first stop NetworkManager:
sudo stop network-manager
And start it again once done. Or reboot :)
In any case, this is frequent when a suspended system fails to wake up. It should be fixed in Maverick.