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LexiKC's avatar
LexiKC
Aspirant
Mar 23, 2018
Solved

R7000 randomly dropping Ethernet connection and changing LAN IP address

Hi all   Router model: R7000 Firmware version: 1.0.9.26   Issue: Since 01/March I've noticed unusual behaviour involving my R7000 and the Ethernet adaptor on my main PC, a bog standard 2014 HP P...
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IrvSp's avatar
IrvSp
Master
Mar 23, 2018

I'd check your MODEM's log.  Check http://www.downloads.netgear.com/files/GDC/LB1110/LB111X_UM_EN.pdf on page 17 on how to log into the modem.

 

At some recent point in the firmware upgrades NG put a fix in so a DHCP IP Address renewal didn't drop the connection. I had that happening too before that fix, it was at least 2 or 3 older f/w that the fix went in. Possible it isn't working on your specific situation?

 

Also check on the routers Advanced page for the CONNECTION STATUS on the INTERNET PORT. How long is your IP Lease for? A short time? That could also be the cause.

 

Wireless would always be on since the router supplies that independant of the WAN connection, just those devices could not use the Internet during that time period or if they did try it would seem to be delayed or even produce some error.

 

Once the device drops the new IP Address if given out by the DHCP server will change depending on which device it handles first, quite normal. One thing you might want to check though, also on the ADVANCED tab is if your WAN IP Address is changing. If so that means the ISP is forcing the change. Could happen on a congested fully utilized server, but I'd think that would be very rare if at all. Worth checking though.

LexiKC's avatar
LexiKC
Aspirant
Mar 23, 2018

Thanks for your reply, IrvSp, but there are no issues with the connection between my R7000 and my LB1110. I've inspected the R7000's logs, and there are no outages or other issues affecting the link from the R7000's WAN port to the LB1110's Ethernet port. 

 

My problem is wholly confined to the way in which my PC and the R7000's DCHP server maintain and assign LAN IP addresses. Based on Case850's post, I expect that I'd see the same issue appear (brief LAN failure followed by a bumped LAN IP address) if I was able to connect my PC to a completely different router-modem combo. What I need to know now is why my PC's IP stack keeps resetting, causing it to request an IP address from the R7000.

  • IrvSp's avatar
    IrvSp
    Master
    Mar 23, 2018

    First you are assuming it seems the PC is causing this? Have you checked the PC's IP Address lease time? Open a CMD prompt and enter IPCONFIG /ALL. It will show you that data, and this is what I see:

     

       Lease Obtained. . . . . . . . . . : Friday, March 23, 2018 1:39:29 PM
       Lease Expires . . . . . . . . . . : Saturday, March 24, 2018 1:39:28 PM

     

    A 24 hour lease which is the standard on a Windows PC. Normally, at 1/2 the lease time the PC will get a new one if it can (can be the same address though), if it can't it will try again later.

     

    Now what MY router sees in its log is problematic:

     

    [Time synchronized with NTP server] Friday, Mar 23,2018 08:08:48
    [Internet connected] IP address: 67.8.xx.xx, Friday, Mar 23,2018 08:08:48

    [Time synchronized with NTP server] Friday, Mar 23,2018 09:34:47
    [Internet connected] IP address: 67.8.xx.xx, Friday, Mar 23,2018 09:34:47

     

    It happens every hour or so. That 'Internet connected' is a request by the router for an IP Address.

     

    Now looking at the Advanced tab on the router's Internet Port Connection Status I see this:

     

    Lease Obtained0 days,1 Hours,38 Minutes
    Lease Expires0 days,0 Hours,17 Minutes

     

    A very short lease was given to the router by my modem/ISP.

     

    My router log is filled with these events:

     

    3/23/2018 12:57680106006

    DHCP Renew - lease parameters tftp file-?BEtyWS2w2vlCvkMKwp3b@CsKd2xSTEBPDiDI3zNL1IiqTmpJF1H9v modified;CM-MAC=b0:da:f9:42:be:43;CMTS-MAC=00:ca:e5:c8:6b:25;CM-QOS=1.1;CM-VER=3.0;

     

    Also these:

     

    3/23/2018 8:574000960006New time has been retrieved from ToD server.
    3/23/2018 9:574000960006New time has been retrieved from ToD server.

     

    Usually the above will match the router logs, but it isn't this time?

     

    Since I know my PC is not the one asking for the new IP Address, and I see a very short 2 hour lease that the router has for the WAN IP Address, I know the problem is somewhere behind the modem (and the ISP agrees, just can't figure it out).

     

    As I said in my first reply, until the R7000 fix came in to handle the IP RENEW request I was getting it dropped and reconnected almost immediately. Doesn't happen now though with the fix.