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    #1

    Ethernet automatic DHCP connection not working

    Hello,

    I can't get the network manager applet to work correctly. The situation is as follows:

    I have a router to which i can connect either wirelessly or wired. The wireless connection works fine. But, when I plug in the ethernet cable, I can't get the wired connection to work. I've disconnected from the wireless network, added a new wired connection with automatic DHCP using the network applet; when I click the wired connection to select it in the network manager, nothing seems to happen.

    The DHCP should work fine, I also have a desktop running Ubuntu and on that one the wired connection works.

    Also, the hardware drivers for the network card are ok; I've actually used a wired connection on this exact system before.
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    #2
    Re: Ethernet automatic DHCP connection not working

    Please paste the contents of the file /etc/network/interfaces into a reply message here. NetworkManager will not manage interfaces that are not commented out. (This is one of the more extreme instances of Linux counter-intuitiveness that I can imagine.)
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      #3
      Re: Ethernet automatic DHCP connection not working

      Code:
      auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
      I assume this is the problem. I've deleted the last two lines and it works now. Thanks a lot!

      I find this behavior strange, any idea why it was programmed this way? At least a warning should be given, that the interface can not be managed because it would override the default settings.
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        #4
        Re: Ethernet automatic DHCP connection not working

        Originally posted by vesrin
        I find this behavior strange, any idea why it was programmed this way? At least a warning should be given, that the interface can not be managed because it would override the default settings.
        NetworkManager is an odd duck, that's for sure. Many people here on KFN prefer to replace it with WiCD. However, since I've grown used to NM's idiosyncrasies, it doesn't bother me so much.
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          #5
          Re: Ethernet automatic DHCP connection not working

          Originally posted by vesrin
          I find this behavior strange, any idea why it was programmed this way? At least a warning should be given, that the interface can not be managed because it would override the default settings.
          If you had the ethernet cable plugged in while installing, then the installer would have configured your connection on a lower level than NM handles. It's not so much Network Manager's, but the installer's fault.
          "The only way Kubuntu could be more user friendly would be if it came with a virtual copy of Snowhog and dibl"
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            #6
            Re: Ethernet automatic DHCP connection not working

            Originally posted by SteveRiley
            Please paste the contents of the file /etc/network/interfaces into a reply message here. NetworkManager will not manage interfaces that are not commented out. (This is one of the more extreme instances of Linux counter-intuitiveness that I can imagine.)
            Actually I think it's quite intuitive if you look at it from an enterprise perspective.

            Even Windows requires you to be an administrator to configure a network interface. Unprivileged users shouldn't be able to override a configuration owned by root if you ask me
            we see things not as they are, but as we are.
            -- anais nin
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              #7
              Re: Ethernet automatic DHCP connection not working

              I am having the same issue.

              It was working fine until I upgraded to KDE 4.7.2 on saturday.

              Now every time I unplug the Laptop to go to work and plug it back in I have to jump through all kinds of hoops to get the connection back. I have to delete the wired connection from nm, then make a new one, reboot, unplug my cable modem and refresh that during boot. sometimes it works and sometimes it doesn't.

              When it does work the connection is excruciatingly slow.

              I have never seen this before. >

              The hotspot over my android phone is faster.

              The KDE forum says:
              don't bother with interfaces configuration file, NM doesn't use that at all. Try looking into NM logs for details, it spits alot of information, maybe you'll find useful information about your problem.
              Has anyone solved this on 4.7.2?

              Edit: Sorry guys, I had this on 10.04 after upgrading to 4.7.2 now I am on 11.10 now but having the same issue after upgrading to 4.7.2.

              Edit2:
              If you had the ethernet cable plugged in while installing, then the installer would have configured your connection on a lower level than NM handles. It's not so much Network Manager's, but the installer's fault.
              That sound dubious. Any way of getting those settings back?
              HP Pavilion dv6 core i7 (Main)
              4 GB Ram
              Kubuntu 18.10
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                #8
                Re: Ethernet automatic DHCP connection not working

                When using DHCP, you system remembers the last few connections you made and tries to connect using the same settings, including the same IP. These settings are stored in the /var/lib/dhcp/dhclient.leases file. What happens is that your router shows that IP as already being assigned and refuses the connection. To force your connection to release the old IP and get a new IP run
                Code:
                sudo dhclient -r
sudo dhclient
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