Problem Cable modem IP add release/renew

BadBoy10 Posts 1 Registration date Friday August 22, 2008 Status Member Last seen August 23, 2008 - Aug 23, 2008 at 11:57 AM
 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



3 responses

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.
tech guy wrt54gs owner
Apr 9, 2009 at 04:23 AM
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 ...
tech guy wrt54gs owner
Apr 9, 2009 at 04:28 AM
here is a link to read about it.