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tssrshot's avatar
New Contributor

Repetitive DHCP Lease Issue

I've got a new routerer installed, and when my lease expires, I have to plug in my old one to get an address before the new one will work. Several other forums suggest calling Cox Support and requesting a DHCP Flush...however, I keep getting dropped from the call. This is three days now, and my very nice, new router (and 802.1c compliant Ethernet Device BTW) cannot work without bringing out an old router from the basement. 

I've tried all the rebooting and unplugging the flow chart tells the Tier 1 guys to direct. This is bigger than that. It's a PFSense Router/Firewall just in case someone is curious, however, its running on an Intel C2758 Server, so no wild cards there. 

Thank You,


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  • Tecknowhelp's avatar
    Valued Contributor II

    What model modem/gateway do you have? If it's a stand alone modem, DHCP should restart each time the modem is reboot. The only ARP cache is on static IPs for Cox business. Can you get a good DHCP lease if you connect a PC direct to the modem and reboot the modem?

  • tssrshot's avatar
    New Contributor

    I believe its the SB6131 or SB6141. Terribly so, I am traveling for work...which is when this typically happens. 

    Yes, If plug in a computer I will pull the typical address and then if I plug the new router in and reboot it will pull that address correctly. However, only until the cycle begins again next DHCP lease expiration. 

    DHCP does not come from the Modem, it only advertises it to the DHCP server and proxies OFFERS, REQUESTS, and ACKS, which is not commonly on the same network subnet as the user end devices. ARP Caches have nothing to do with this typically, as DOCSIS is a layer 2 technology and the IP to MAC mapping doesn't apply when you don't have an address yet. If there WAS an ARP Cache issue it would be because the next router in the path is not purging ARP entires when they expire or is otherwise misconfigured (like enabled Proxy ARP, etc.)  

    I've scoured several other forums regarding this and a lot of commercial routers have this issue with Cox (by name).  If you wait long enough on hold or get the just lucky tech who understands that there is possibly a DHCP FLUSH issue on the server side. This is further evident by the fact that I cannot resolve this issue by Spoofing the MAC of a computer or secondary device. 

    I believe Cox might have misunderstood me, when I wrote this thinking i was merely venting, but I actually would prefer them to solve and fix this issue. This has been ongoing for several years for other customers and instead of resolution they often move to another Company. Guess what CenturyLink offers 1Gb in my neighborhood for $20 less than what I am paying for non-working service.