How to force Comcast IP address to change

Published July 22, 2022

If you use Comcast Cable Internet service, you've probably noticed that the IP address hasn't changed for over a year and even though Comcast service tech support says your IP is dynamic, it's really pretty much static (saving you the static IP fee).

Comcast XFinity Internet

For some reason, if you need to change your external IP address, Comcast support will tell you to do a power cycle which is basically:

  • Turn off your router and Comcast modem.
  • Wait for 20 seconds (or upto 2 minutes).
  • Turn on the Comcast modem, wait for a minute and then turn on the router.
  • You should have a new IP address.

Unfortunately, this doesn't work most of the time when you're behind a router (Linksys WRT-54G in my case). Comcast insists that your IP is changed, but a quick check of my IP address shows that my IP is still the same.

The real solution to this is to change the MAC address of your WAN device in your router configuration:

DISCLAIMER: The solution involves changing your MAC address. If you mess up your modem or router, do at your own risk. I'm not liable for anything.

  • Login to your router configuration { Linksys: }
  • Navigate to the MAC address section and to the WAN MAC address.
  • Change the last digit of the MAC address. Don't change anything else.
  • Now do a power cycle. Turn off the modem and router.
    In some cases, you'll have to reset the Comcast modem using a paper clip or tip of pen if a regular power cycle doesn't work.
  • Wait for 2 minutes and turn on the Comcast modem (yes, I know 20 seconds is usually enough, but 100 seconds more will not hurt.)
  • Turn on the router, wait till it boots up and check your IP address. It should be different.

NOTE: If you still cannot change your IP address, let me know. Note that I do not offer technical support of any kind and all my responses will be voluntary.

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Last Updated: July 22, 2022.     This post was originally written on January 13, 2011.