3 Replies Latest reply: Mar 8, 2013 1:48 PM by Bob Timmons
kthunter2 Level 1 (0 points)

I have an Airport Extreme, and had is set up in DCHP & NAT mode for the network. Recently a new modem was put in my ISP, and for some reason the Airport can only operate in bridge mode. This creates problems for my AT&T Microcell. Suggestions?

iMac, OS X Mountain Lion (10.8.2)
  • Bob Timmons Level 10 (98,354 points)

    It sounds like your new "modem" is not really a modem at all, but a combination modem/router or gateway type of device that combines the normal functions of a separate modem and separate router in one package.


    Can you provide the make and model number of this device so that we can confirm on exactly what you have there?


    You only want one router on a network provinding DHCP and NAT services, and if your new "modem" is doing this, then the AirPort Extreme needs to be configured in Bridge Mode to avoid IP address conflicts and NAT errors.


    Check with your ISP to see if they can provide you with a simple modem.....not a modem/router or gateway.....that will allow the AirPort Extreme to correctly act as the router for your network, providing DHCP and NAT services.

  • kthunter2 Level 1 (0 points)

    The new modem is a combined modem, router and WiFi device. It is an Arris DG860A, and the WiFi on it is disabled-only the Airport Extreme is broadcasting a WiFi.


    This was the modem they would only allow, as I suppose it provided a higher level of bandwith. 

  • Bob Timmons Level 10 (98,354 points)
    This was the modem they would only allow, as I suppose it provided a higher level of bandwith.


    Check with the ISP to see if the Arris modem/router can be configured to act as a bridge mode modem only. That would allow it to function as a simple stand alone modem, which is what you need.


    Otherwise, you can try running the AirPort Extreme in the Double NAT error condition, but I do not recommend that you do this, as this will slow down your Internet connection and possibly create communication problems from one device to another on your network.


    If you have not already done so, try plugging the AT&T Microcell into the Arris gateway to see that will allow it to function correctly.