LAN not working on 17.04
Actually yesterday I've upgraded from Ubuntu 16.04 to 17.04 and I got a problem that, if connect LAN cable it does not showing anything and remains disconnected. But i can connect with WiFi. I don't know what's the problem. Actually its showing "device not managed" under the "Ethernet Network" and both were disabled. I've searched for the solution, but did not found yet.
Here is the fix for the LAN problem that first occurred mildly in 16.04, got a bit worse in 16.10 and became unbearable in 17.04 rendering it unusable:
sudo touch /etc/NetworkManager/conf.d/10-globally-managed-devices.conf
sudo service network-manager restart
This creates a blank file needed in the /etc/NetworkManager/conf.d directory which the installer fails at creating automatically. The real question that should be asked is why are such critical things left unresolved for so long to cause needless worry and lost time for many people?
UPDATE: In addition to the above, the culprit seems to be the file with the same name in /usr/lib/NetworkManager/conf.d/. Either comment out (by inserting a hash at the beginning of each line) or delete all its contents to make it a blank file using a text editor such as gedit:
sudo tee /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf < /dev/null
Alternatively, backup the existing file, and add e.g. _backup to its name to be safe, and create a new blank file. I actually went back to 16.04LTS for a while due to this problem, but now the networking is functional under 17.04.
Most probably your interface appears in /etc/network/interfaces. By default, NetworkManager does not manage interfaces that appear in /etc/network/interfaces. You can change this behaviour.
To do this - in a terminal:
sudo nano /etc/NetworkManager/NetworkManager.conf
change the line managed=false to managed=true
Save, stop and start network manager:
sudo service network-manager restart
EDIT 1
Try this. Remove the interface from /etc/network/interfaces.
backup the current interfaces file:
sudo cp /etc/network/interfaces /etc/network_interfaces_backup
Then open the file:
sudo nano /etc/network/interfaces
Delete everything in that file and copy and paste the following:
auto lo
iface lo inet loopback
Save, stop and start network manager:
sudo service network-manager restart
After this check that you have Enabled Networking ticked
This solved my problem. Edit this file:
sudo -H gedit /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf
You need to explicitly add ethernet devices to be managed. To do so the contents of the file should be like this:
[keyfile]
unmanaged-devices=*,except:type:wifi,except:type:wwan,except:type:ethernet
After that, just restart the NetworkManager service:
sudo service network-manager restart