Help! Change/Refresh Airport Extreme IP address ( Router Address)

Discussion in 'Mac Accessories' started by stealthmode29, Feb 11, 2016.

  1. stealthmode29 macrumors member

    Mar 24, 2011
    Hello, would anyone possibly know how to refresh or change the IP address of my Airport Extreme? I am talking about the one that you see when you open Airport Utility and click on the icon of the router. It seems that no matter what I do, the IP address is always the same- I've done all types of resets and even brought it back to the factory defaults, yet no matter what I do, it always stays the same. To elaborate, I have a cable modem that is plugged into the router. My cable modem provides a dynamic IP address. I know for a fact that it changes every so often sometimes even after just unplugging it for a few hours. When I plug the modem directly into my iMac, it displays the appropriate IP, however, when I put the router back into the equation, and check my IP address, it is always the one listed in airport utility as I mentioned in the beginning. Is that IP address specific to the hardware ??? I have even contacted apple willing to pay for the answer but after 25 minutes on hold, the rep came back with nothing. I have read about similar posts to mine, but none ever showed a real solution. Question is, what is dictating that IP address? Where is the problem, ISP side or Router? Any input is much appreciated as I've been racking my brain to find the solution. Oh and by the way, the whole reason I want to refresh it is because of security reasons. Many thanks.
  2. Alrescha macrumors 68020

    Jan 1, 2008
    You will probably have to call your ISP and ask them if they would pretty-please delete the MAC address of your Airport Extreme from their DHCP server.

    Alternatively, you could leave your Airport Extreme unplugged until your ISP forgets about it. Depending on your ISP, this could take a very long time (weeks, months).

  3. stealthmode29 thread starter macrumors member

    Mar 24, 2011
    So the MAC address of the router is what is dictating it's IP address?
  4. Alrescha macrumors 68020

    Jan 1, 2008
    Well, your ISP is dictating the IP address. In many (most?), but not all, cable Internet installations, it works like this:

    Your cable modem acts as a bridge between the cable system and your Ethernet network. It is often transparent or invisible to traffic.

    So, whatever device you plug into your cable modem asks for an IP address when it boots and this request gets passed along by the cable modem to equipment upstream - the DHCP server.

    The DHCP server sees the MAC (media access control) address of whatever asked for an IP address and finds a free IP address to give out. It remembers the MAC address and the IP, and will usually give out that IP to that MAC until it forgets. The "D" in DHCP means "dynamic", which in network terms just means 'not guaranteed to be the same every time'. It does not mean 'guaranteed to be different every time'. :)

    If you plug in a different device, the DHCP server will go through the same routine and give that device an IP address. If you switch back to the original device, the DHCP server remembers it and gives it back the old IP address.

    How long the DHCP server remembers the address pairing is up to the ISP.


    nb: If you call your ISP, it might be simplest to tell them you need a different IP address. The person who answers the phone may not know anything about DHCP servers and will have to pass the request on to someone who should know what to do.
  5. stealthmode29 thread starter macrumors member

    Mar 24, 2011
    Alrescha, thank you so much for taking the time to answer my question. I'll try contacting the ISP and see what they say.
  6. adam9c1 macrumors 68000


    May 2, 2012
    Do you have a modem or a router from your isp?

    If ISP put your airport in bridged mode.

Share This Page