Wired Connection – Fix ‘Wired Unmanaged’ Issue in Ubuntu 18.04

I recently upgraded to ubuntu 18.04 but I'm facing issues with the wired connection. First off, I must say that the wifi connection is working fine.

When I start my computed I don't even get the wired network icon. Going into the settings/Network parameters, I don't see anything about wired connection (only VPN and proxy).

Thus I tried to understand what was happening and I used a couple of different commands:

~$ lshw -C network 
WARNING: you should run this program as super-user.
*-network                 
   description: Wireless interface
   product: Wireless 8265 / 8275
   vendor: Intel Corporation
   physical id: 0
   bus info: pci@0000:01:00.0
   logical name: wlp1s0
   version: 78
   serial: 00:28:f8:f8:80:b8
   width: 64 bits
   clock: 33MHz
   capabilities: bus_master cap_list ethernet physical wireless
   configuration: broadcast=yes driver=iwlwifi driverversion=4.15.0- 
22-generic firmware=34.0.1 ip=10.4.26.243 latency=0 link=yes multicast=yes wireless=IEEE 802.11
   resources: irq:144 memory:dc100000-dc101fff
*-network DISABLED
   description: Ethernet interface
   physical id: 2
   logical name: enx3c18a070d46d
   serial: 3c:18:a0:70:d4:6d
   size: 1Gbit/s
   capacity: 1Gbit/s
   capabilities: ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
   configuration: autonegotiation=on broadcast=yes driver=r8152 driverversion=v1.09.9 duplex=full link=no multicast=yes port=MII speed=1Gbit/s

Then I decided to enable the ethernet interface as follows

sudo ip link set enx3c18a070d46d up

The result of the "lshw" command does not show DISABLED anymore. The wired connection icon came back but still no internet connection and now showed the following message

Wired unmanaged

I would be very interested if any of you have an idea about how to solve this problem.

Thank you and have a good day.

Finally, here are the results of a couple of commands (note that ifconfig is obsolete on ubuntu 18.04)

~$ ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN     mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: wlp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DORMANT group default qlen 1000
link/ether 00:28:f8:f8:80:b8 brd ff:ff:ff:ff:ff:ff
3: enx3c18a070d46d: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc     fq_codel state UP mode DEFAULT group default qlen 1000
link/ether 3c:18:a0:70:d4:6d brd ff:ff:ff:ff:ff:ff

~$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
   valid_lft forever preferred_lft forever
inet6 ::1/128 scope host 
   valid_lft forever preferred_lft forever
2: wlp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state 
UP group default qlen 1000
link/ether 00:28:f8:f8:80:b8 brd ff:ff:ff:ff:ff:ff
inet 10.4.26.243/23 brd 10.4.27.255 scope global dynamic noprefixroute wlp1s0
   valid_lft 42269sec preferred_lft 42269sec
inet6 fe80::11e5:2546:9014:171b/64 scope link noprefixroute 
   valid_lft forever preferred_lft forever
3: enx3c18a070d46d: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc 
fq_codel state UP group default qlen 1000
link/ether 3c:18:a0:70:d4:6d brd ff:ff:ff:ff:ff:ff
inet6 fe80::3e18:a0ff:fe70:d46d/64 scope link 
   valid_lft forever preferred_lft forever