Problem Cable modem IP add release/renew [Solved/Closed]

BadBoy10 1 Posts Friday August 22, 2008Registration date August 23, 2008 Last seen - Aug 23, 2008 at 11:57 AM - Latest reply:  eliytuangson
- Apr 7, 2012 at 10:01 PM

I have finally been able to release and re-new my cable IP address after speaking with my cable provider. It was a real nightmare.

I have a linksys router WRT54G and connected with a cable modem. For the last 2.5 years, my IP adddress has not changed as my network is always on.

Anyway, I have decided to change my IP address.


my router was giving the IP and when I connected a laptop to the modem direcly I got the same IP .

Anyway, I did remove the coaxial cable from the cable modem, and turn off the modem.

2 hours later, reconnected the coaxial cable to the cable modem, then went to command promt (laptop connected directly to the cable modem, did ipconfig/release then ipconfig/renew.

to my surpise the IP address got release and was getting a new IP address from my cable modem instead

I connected the modem back to the router and did a ping, and to my surprised thru the router I got the original IP I can not understand why, I did a hard for the router, and reconfigure it, and still that IP address keep popping up, while the cable modem is if I still connect the laptop to the modem.

Do I need to something in Vista to sort this problem? I want my router to give the new IP address of the cable modem?

any advice would be appreciated


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4 replies

Best answer
Thank you
I believe this has something to do with MAC address of the router, as the modem stores such information and makes a lease query based off that address (the modem itself most likely doesn't receive own external IP, yet in most cases accessible via web-interface - i.e. for Motorola models, google for your make. For this, I presume, you must be directly connected to the modem with one of your systems). One of the ways to resolve it would be spoofing router's MAC (if possible at all), another - reseting the cable modem to the factory default to clear MACs stored in modem's memory, which is easier to do via web-interface, but I wouldn't recommend it without notifying and hence receiving a blessing from your ISP first, as I'm not a professional and have only a vague understanding of the consequences, moreover never tried it before myself. As for what can you do to make the IP release/renewal easier next time - as far as I understand there is nothing to be done on the user side except what was already mentioned: reseting to factory defaults or spoofing router's MAC, which is probably not that easy to do, if that option is not openly available on your model.

Thank you, Nick 4

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tech guy wrt54gs owner - Apr 9, 2009 at 04:23 AM
Thank you
install the ddwrt firmware on your router iw will solve your problems .
Thank you for posting this article in this forum I will bookmark this page and tell my friends about this ...