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Forum Discussion

insanesquirle's avatar
Sep 21, 2017

DHCP Not working

My once fine-working cable modem has randomly stopped assigning IPV4 addresses to all of my devices.  IPV6 is on auto-assign and works fine.  I verified that IPV4 is set up for DHCP, but none of my devices are receiving an IPV4 address.  

If I manually assign an IPV4 address to a device it works fine and I am able to access anything on the web.  I've tried rebooting, and then factory resetting, still not working.

I used the netgear utility and my firmware is on its latest version.

Firmware version: V2.01.22

This is happening on wired and wireless devices.

 

Any ideas?

5 Replies

  • Same thing happened to me. I'm on an older Firmware of 2.01.14

    I disabled DHCP, rebooted, enabled it, rebooted again and now it's working. We will see for how long.

    • antinode's avatar
      antinode
      Guru

      > Re: DHCP Not working

         How do you know that the fundamental problem is DHCP, and not, say, a
      totally broken connection?  As usual, showing actual actions with their
      actual results (error messages, LED indicators, ...) can be more helpful
      than vague descriptions or interpretations.  What observations, exactly,
      led you to this "DHCP Not working" conclusion?

         Do the LED indicators on a wired connection (both ends) always look
      good?

         If you have a computer with a suitable static IP address (so that it
      doesn't need DHCP from the router), preferably wired, can you always

      talk to the router's web site?

         Many things can leave a computer/device without a good IP
      configuration.  A bad DHCP server is only one of them.

      > I disabled DHCP, rebooted, enabled it, rebooted again and now it's
      > working.

         How much of all that necessary?  Will a simple reboot do the job?

         Depending on how deep you want to dive, it may be possible to probe
      the operation of the router at a lower level.  There are various
      programs out there which may be able to enable a Telnet (command-line)
      interface to many Netgear routers.  (I use the program which I modified,
      http://antinode.info/nte , but others are available).  Around here
      (D7000, V1.0.1.54_1.0.1), for example, I can see if the DHCP server is
      running:

      # ps | grep -i dhcp
       1152 root       704 S    /var/udhcpd_1 /etc/udhcpd.conf1
      [...]

      That doesn't prove that it's working, but if it died, then that would be
      detectable and interesting.

      • Bryansix's avatar
        Bryansix
        Aspirant

        The telnet thing is interesting. I'll have to check that out when I have time.

         

        I rebooted the router at least 6 times. I tried both a hard power cycle by taking out the power cable and a soft reboot via the web interface. I had connectivity to the router via ethernet and wifi on my computer and neither were getting a DHCP address. ipconfig / release && ipconfig /renew did nothing. Only once I disabled DHCP, rebooted, enabled it, and rebooted again did it finally start assigning IP addresses again.

         

        One thing to note is that the router seems to have lost its time as some point because some of the logs look like they are from 1970.