Laptop lan port - not working

I have three ThinkPads.
One has Kubuntu, one has Neon, one has Ubuntu.
I had a wireless issue with my router so I plugged each into
the router - none of them will get an address.

The ThinkPad with Neon just had Windows 7 and the port
is/was working. So at least that one I can say - the port isnt
bad. However, Ive used the other two for along time to program
wireless radios so I can say those ports - at least as of last night -
while connected to a radio - seems to be working, though Ive
not have either connected to a network in a very long time.

Ive verified that all ports on my router work but plugging other
things in. Ive tried changing cables - none of the laptops pickup
and ip. Ive disabled wireless - just in case -on each laptop.

My wifes ThinkPad - windows 10 - picks up a ip and runs just fine.

This is very strange (to me)
Anyone have some ideas for me to try?

More info needed
Try these from the command line
ip addr
ip route
show us what you get

Also do you have NetworkManager running? try
ps ax | grep Net
it will tell you.

And what do you have in
/etc/network/interfaces file?


In some Linuxes (Linii) there is a button in the panel which brings up network interfaces and offers to connect or disconnect. If you have this button, what does it bring up?

ip addr:
1: lo <loopback, up , lower_up>
2: enp1s0<broadcast…>
3:wlp2s0: <broadcast…>

ip route: produces nothing
ps ax | grep Net:
591? Ssl 0:05 --no-daemon
11881 pts/1 S+ --color=auto Net

if-down.d, if-post-down.d, if-pre-up.d, if-up.d

On the button, bottom right, networking icon, Wired connection1: setting network address - it just spins. It will never connect.

Network controller: Realtek Semiconductor, RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 7), Kernel driver in use: r8169, kernel modules: r8169

You do not have NetworkManager running, and there is no interfaces file in /etc/network

So , unless you have dhcpcd or some other network daemon running, there is nothing to bring up a network.

I think I would try installing NetworkManager. That would be the simplest way. It will usually find an ethernet connection that has DHCP, completely automatically, ie you dont need to configure it. It can be a bit of a beast if there is more than one ethernet card.

You may find that your system has a GUI called somethting like ‘Connections’. These GUI’s are basically a management screen for NetworkManager, but they are generally poorly designed and very confusing. Use it if you have to, bjt it is my guess that NetworkManager will come up unaided once you intall it and reboot.


So, why does wireless work? Would it not use Network Manager?

network-manager, network-manager-pptp is installed per Muon Package Manger.

Thinkpad E495 running Ubuntu 20.04 : plug and play LAN port… just works… never have to do anything other than plug the UTP cable in…

Me either - ever … until today.

Wireless might use NetworkManager if it were running

OK so it is installed. Maybe the Networkmanager daemon needs to be started? Or maybe the daemon is called something else and the grep did not find it?

Try which NetworkManager
that will see if the command to start it is present.
If it is there, do
sudo NetworkManager &
That should start it and put it in background.
Not sure if you need any optional arguments on that, but give it a go, probably ok. Cant do any harm.

If it isnt there, we have to try and find what its name is?

Cheers Neville

So how do you think he got into this state?
Not likely to be a HW issue.
Must have been configured for Wireless only?

If he needs to start the daemon, can you tell him how to do that with systemd? I dont know about systemd. What I told him to do will only start it for the current session.


Shouldn’t hardly ever need to touch networkmanager daemon…

I do occasionally when I can’t get a new tun (tunnel) device on my works VPN - so I restart network manager and that usually sorts it :

sudo systemctl restart NetworkManager.service

But as stated above - I NEVER have to do this for WiFi or LAN / ethernet…

Me either. Why isnt it running? The ps ax | grep net failed to find it?
Only time I touch it is to kill it and configure manually.

What’s your netplan config say? Mine (Ubuntu 20.04) defers to NetworkManager :

cat /etc/netplan/01-network-manager-all.yaml 
# Let NetworkManager manage all devices on this system
  version: 2
  renderer: NetworkManager

However - on things like Ubuntu server (18.04), we don’t use NetworkManager, we use networkd :

cat /etc/netplan/01-netcfg.yaml 
# This file describes the network interfaces available on your system
# For more information, see netplan(5).
  version: 2
  renderer: networkd
      addresses: [ x.x.x.x/24 ]
      gateway4: x.x.x.x
          search: [ ]
              - "x.x.x.x"
              - "x.x.x.x"

I’ve redacted specific site information (hence x.x.x.x and

Thanks, its not me it is Wade’s laptop.
We will have to wait and see what he says to your question

OK - sure - I can’t say what the filename will be, 'cause it varies from release, or desktop VS server - but - there will likely only be one file called 01-*.yaml in /etc/netplan/ (or something like that).

I miss the tool on OpenSuSE called wicked which configures both ethernet and wireless as a service when booting up before the Desktop. I wish, really wish, KDE Neon had a tool like that. If it does, please enlighten me. TIA


version: 2
renderer: NetworkManager

That is all that is in the file.

Devuan 3 had wicked. They took it out in Devuan 4.

Do they not have it as a package which you could install? You would need to stop other network daemons, if you used wicked.


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