After starting the OS, there is no internet connectivity. The network manager shows that eth0 and wlan0 are not managed.
Make sure that the eth0 and wlan0 are discovered. Run the following command.
ifconfig -a
If the ethernet and wlan can be seen in the output but no ip address is allocated to it, check if the dns nameserver exists.
sudo gedit /etc/resolv.conf
If this list is empty then add the following entries in it.
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 8.8.8.8 nameserver 8.8.4.4
These point to the Google DNS.
Try to ping any website. Example:-
ping www.google.com
If the result is successful we have a working conncetion.
If ping fails, then the system doesn’t manage the network drivers.
For the system to manage the network devices, we have to make changes in the /etc/NetworkManager/NetworkManager.conf file
sudo gedit /etc/NetworkManager/NetworkManager.conf file
The displayed output will be in the format:-
[main] plugins=ifupdown,keyfile,ofono dns=dnsmasq no-auto-default=XX:XX:XX:XX:XX:XX, [ifupdown] managed=false
Change the managed value from false to true
[main] plugins=ifupdown,keyfile,ofono dns=dnsmasq no-auto-default=XX:XX:XX:XX:XX:XX, [ifupdown] managed=true
Restart the network service
sudo service networking restart.