I am running a lubuntu 14.04 server and its always worked well, except for the last couple of days it keeps dropping off the LAN. I am using a couple of powerlink adapters to connect it up as WiFi was never very solid on it.

Anyway, I plugged a screen and mouse/keyboard into it to try to work out whats up with it, and I tailed the syslog. Here is an excerpt: http://pastebin.com/4ftXsai4

Can someone please give me any clues to what might the problem be? Or any tips on how to track down the issue.

I have unplugged the Ethernet cable from my router and rebooted it all, to no avail.


I'm not sure what happened. But the server has been up, connected all day today. I am tailing a log file via a remote SSH connection and its not disconnected once.

Could have been that the WiFi card was playing up, or the router was struggling to assign DHCP, although, if it was a DHCP problem, why would it keep disconnecting?

  • A guess, your DHCP service is not working and/or is having problems with IPv6.
    – mdpc
    Jan 14, 2015 at 21:28
  • I powered down and removed the WiFi card, and now it seems to be working again properly... Odd?
    – Chris
    Jan 14, 2015 at 21:35
  • not really....your power cycle probably fixed some type of glitch.
    – mdpc
    Jan 14, 2015 at 21:42
  • Nope, after 10 mintues, it went again!
    – Chris
    Jan 14, 2015 at 21:47
  • I powered it all off last night, today it seems to be staying up okay. Infact it stayed up long enough to run through a whole bunch of updates.
    – Chris
    Jan 15, 2015 at 10:56

1 Answer 1


The logs show that the Ethernet card lost carrier (i.e. it was "disconnected") before 20:48. When it enables the interface and tries to obtain an IP address through DHCP the queries go unanswered:

Jan 14 20:48:31 plex dhclient: DHCPDISCOVER on eth0 to port 67 interval 11 (xid=0x6c7ab96a)

As it cannot obtain an IP address, Network Manager gives up on the interface and defines the interface as 'Disconnected' (20:49:09) with the log:

NetworkManager[828]: <warn> Activation (eth0) failed for connection 'Wired connection 1'

Three seconds later it tries again to configure the interface. Again, without success, as seen in the DHCDPISCOVER queries sent at 20:49:12, repeated 4 times in the logs until it probably considers it (not show in the logs) as disconnected.

There might be either a problem in the DHCP server (maybe it broke and stopped providing IP addresses) or in the network driver or card (packets are not not sent to the network, including the DHCPOFFERs, there were no seen nor answered) or in the cabling.

In order to confirm if there is a problem with the DHCP server, driver or cabling, I would suggest you configure a static IP address in the network card by modifying the network configuration for eth0 through Network Manager.

Once you have configured it with a static IP address. Try to keep in the system a constant stream of traffic through the network (e.g. using 'ping ') for at least 24 hours.

Interrupt it after that an look at the statistics: have packets been lost? how many? This would be an indication of a problem in either cabling or the device you connect to.

Note: If you do not want to keep a console open, in order to keep this running in a disconnected console you can use screen to keep the network ping working, disconnect the console and reconnect to it when you want to review the results.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .