Wired Connection not working in Ubuntu 18.04

Question

Wired connection was not identified by Ubuntu.

Here's my result if I run ifconfig -a on terminal

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
    inet 127.0.0.1  netmask 255.0.0.0
    inet6 ::1  prefixlen 128  scopeid 0x10<host>
    loop  txqueuelen 1000  (Local Loopback)
    RX packets 308  bytes 22700 (22.7 KB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 308  bytes 22700 (22.7 KB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

 wlp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 10.42.0.249  netmask 255.255.255.0  broadcast 10.42.0.255
    inet6 fe80::a78:589e:2107:b3c4  prefixlen 64  scopeid 0x20<link>
    ether dc:53:60:e2:ce:99  txqueuelen 1000  (Ethernet)
    RX packets 13416  bytes 9588247 (9.5 MB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 9109  bytes 1698278 (1.6 MB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Help me to get out of this

Thanks in Advance :)

Answer 1

The following helped me (I'm not quite sure why, but it did! :D)

Check ethernet state with

$ nmcli device

Check if there are errors or warnings from NetworkManager

$ systemctl status NetworkManager.service

Go root:

$ sudo -s

Delete all files in the directory /var/lib/NetworkManager/ except secret_key

$ cd /var/lib/NetworkManager/
$ rm -v !("secret_key")

Now reboot system and check ethernet state with nmcli device

If that does not help, you can create an empty file with this command and restart the computer again. sudo touch /etc/NetworkManager/conf.d/10-globally-managed-devices.conf

Source: https://forum.ubuntuusers.de/topic/kein-netzzugriff/