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Kronzee21's avatar
Kronzee21
Follower
Jan 12, 2023

Router/modem issue

i have a question, I recently switched internet services. From spectrum to att. When I used the spectrum modem it was easy to use my third party router to change my mac address and therefore my public ip address. however now when i try to change my mac address with att what happens is the modem just changes the ip address of my router when i change the mac address. My public IP address stays the same. Why? What is going on here? Please help

2 Replies

  • michaelkenward's avatar
    michaelkenward
    Guru
    Jan 13, 2023

    Which Netgear router are you using?

     

    What firmware version do you have on the device?

    A number is more useful than "the latest". (It may not be by the time people read this.) There can also be newer versions, or "hot fixes", that do not show up if you check for new firmware in the browser interface.

    It might also help if you told people what the modem is in front of this router, if there is one. The make and model number could be useful. Is it, by any chance, also a router, with a set of LAN ports on the back?

    The reason for asking is that a lot of people turn up here trying to put a router behind a modem that is also a router. That can complicate troubleshooting.

    Did you reset your router when you changed ISP?  You have to do that to get it to forget settings from the old ISP.

     

    How do I perform a factory reset on my NETGEAR router? | Answer | NETGEAR Support

    • plemans's avatar
      plemans
      Guru
      Jan 13, 2023

      spectrum uses modem only devices. ATT uses modem/router combo devices as gateways. And it causes a double nat. 

      A double nat happens when you cascade more than 1 router.
      https://kb.netgear.com/30186/What-is-Double-NAT
      Fixes? There’s 3 options but only use 1.
      1. Put the modem/gateway in modem only/pass through mode. This disables its routing functions.
      2. Leave the modem/gateway in router mode but put the Netgears IP address into its DMZ. This forwards the data to the netgear. You can either leave the modem/gateway’s wireless enabled or disabled. Just make sure its using a different wifi channel to prevent interference
      3. Put the Netgear into access point mode. This disables its routing functions. Wifi/ethernet still works but it does disable some features.
      https://kb.netgear.com/26765/Which-features-are-disabled-on-my-NETGEAR-router-when-it-is-set-to-AP-Mode