Cannot connect to wired connection on Ubuntu (SOLVED)

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Howtos / System Administration

When your Wireless interface is working and the ethernet isn’t working on Ubuntu, here’s a quick howto to check and fix a misconfiguration. It doesn’t solve any ethernet issues but you can give a try and on an Asus laptop (with JMicron chipset) I worked on it makes the job done.

Tested on Ubuntu 16.04 LTS

First steps

To detect Ethernet interface:

ifconfig

To check and configure connection:

apt-get install ethtool

To save the current status of network interface:

ethtool ens5f5 > ethernet_before.txt

Make ethernet interface works

ethtool -s ens5f5 speed 1000 duplex full autoneg on

or:

ethtool -s ens5f5 speed 100 duplex full autoneg on

Then to check what is the difference between the old non-working configuration and the configuration that works:

ethtool ens5f5 > ethernet_after.txt
diff ethernet_before.txt ethernet_after.txt

If it doesn’t work try other ways, e.g. looking for specific issue on your Ethernet driver:

lspci | grep Ethernet

or

lspci | grep ethernet

to check your driver.

If the issue reappears after reboot, to make the command to run on startup do:

sudo bash
crontab -e

And add:

@reboot /sbin/ethtool -s ens5f5 speed 100 duplex full autoneg on

Now reboot to check if changes takes effect

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