Cannot access Internet after 14.04 upgrade

Solution 1:

1. In /etc/NetworkManager/NetworkManager.conf, change managed=false to managed=true.
2. From the top-right corner select Edit Connections, and add a new connection. Specify your ip address, netmask, gateway, and the DNS server being 8.8.8.8.
3. Then run: sudo service network-manager restart.

Solution 2:

Edit correctly the following files:

/etc/network/interfaces
/etc/resolv.conf
/etc/hosts

In /etc/network/interfaces specify these information:

 auto ethX
    iface ethX inet static

    address
    netmask
    broadcast
    dns-nameserver
    gateway

ethX: X can be 0,1, 2 ... depending on the network interface you are using. But in your case it is eth0

In /etc/resolv.conf specify these information:

nameserver x.x.x.x

(you can add a new nameserver address on a new line)

In /etc/hosts add your username and address on the 3rd line as follows:

  yourUsername yourIPaddress

After you saved the 3 files, run this command:

sudo service network-interface restart INTERFACE=eth0

Solution 3:

After several tinkering of the settings with helps from various readers here, the situation had not been improved.

So, I eventually backed up all the important files and did a full install of 14.04. Now the system is capable of getting to the internet and internal networks. There are, however, a few "glitches" in 14.04 gnome comparing to 13.10. But at least I can use my system again.

Thank you for those who lent a helping hand.

Solution 4:

I had the same problem with my WiFi connection , I tried to edit Newtworkmanager.conf but didn't work for me .

I went to edit connection and deleted my Wifi connection Then added it again and entered the password ...

and It fortunately work :)