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I used to change my MAC address in my router configuration all the time in the past. However, I recently upgraded with my ISP and they installed a new cable modem. What I normally do is modify the last digit of the MAC address (to an allowable character of course), and then unplug my modem and router. Since the new modem installation though, the internet doesn't work after I do that. After changing the last digit of the address back to the original one, it works again. Is there something in the upgrade that's restricting me from changing it or something?

My router is a Cisco Linksys E3200 and my modem is a Cisco DPQ3212. My ISP is Cox.

Thank you.

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Describe the clearer the connection diagram. What you are doing. Connect directly? Connect devices to each other? Only installing Cisco Linksys E3200? – STTR Jun 26 '13 at 13:36
Please describe which component does what (NAT, …). BTW: Why do you want to modify the MAC address anyway? – Marcel Waldvogel Jun 26 '13 at 14:04
Cox registered the MAC address to avoid certain actions by their customers they decided was not worth doing. You will have to contact COX and tell them the new mac address of the modem. – Ramhound Jun 26 '13 at 14:09

Does your modem have a backup battery? You may need to use a reset button on the modem to truly reset it.

It's possible the cable modem may have recorded the MAC address of your router in its NVRAM, or your ISP has recorded it, and you will need to call them to tell them to clear it.

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Cisco DPQ3212:

Cisco DPQ3212

How to clone a MAC address

On any home network, each network device has a unique MAC (Media Access Control) address.Some ISPs register the MAC address of the device (usually a router or a computer) connected directly to the modem.If your computer’s MAC address is registered with your ISP and you do not want to re-register the MAC address, then you can clone the address (assign the registered MAC address of your previous device to your new router).If you want to use the MAC address from an old router that you are replacing with your new router, you should first determine the MAC address of your old router, then manually enter it into your new router.


For many ISPs that provide dynamic IP addresses automatically, the stored MAC address in the modem is reset each time you reset the modem.If you are installing this router for the first time, reset your modem before connecting the router to your modem.To reset your modem, disconnect power for about one minute, then reconnect power.

To clone a MAC address from your computer:

Setup > MAC Address Clone

  1. Log into the browser-based utility (see “How to open the browser-based utility” on page 21).
  2. Click the Setup tab, then click the MAC Address Clone page.
  3. Click Enabled.
  4. Click either Clone My PC’s MAC or enter the 12-digit MAC address of your old router.
  5. Click Save Settings.

E3200 Menu:

E3200 Menu

E3200 clone Mac Address:

Clone Mac Address

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