Ubuntu – No internet after upgrade from 17.10 to 18.04

18.04networkingupgrade

After upgrading from 17.10 to 18.04 today, I have no internet connectivity, either wired, or wireless. Output from ip link suggests interfaces are all up, though they do have strange names. I tried the solution at https://answers.launchpad.net/ubuntu/+question/665374 but it didnt work for me. Suggestions as to how to debug this would help! Unfortunately, as I have no internet, it's hard to post evidence…

Best Answer

Same issue faced...following worked for me:

identify what is your ethernet interface with command $ifconfig

in my case that is: enp2s0 Then add following lines in /etc/network/interfaces

$sudo cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
auto enp2s0
iface enp2s0 inet dhcp

In my file last two lines were not there....once I enter those lines and given command 

$ sudo ifup enp2s0

After that I inserted my LAN cable and it started working fine.

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