4 Replies Latest reply: Nov 13, 2013 2:36 PM by steelbom777
steelbom777 Level 1 Level 1 (5 points)

Hi,

 

I'm getting a "double NAT warning" on my 2013 AEBS.

 

It's set up to handle DHCP/NAT. The modem from my ISP has had DHCP/NAT disabled, and it's connected to the AEBS via ethernet cable.

 

Randomly, sometimes once every day, or two, or three, the internet just stops working because of this error. Sometimes it's sorted itself out from me just leaving it for 15-30 minutes, other times not.

 

It's happened maybe ten times since I've had this AEBS (which is about three months), and two or three times in the last few days.)

 

Usually, I restart the AEBS, and then it starts working correctly in a few minutes.

 

What could cause this?

 

Below is a screenshot of the error message:

(Note that the last time it happened I selected to ignore it, but prior to that it wasn't.)

Double NAT AEBS Error.png


iMac (21.5-inch Mid 2011), OS X Mavericks (10.9)
  • LaPastenague Level 8 Level 8 (42,790 points)

    what kind of modem do you have? Make and model?

     

    You hid the stuff that for double NAT i need to know.. when you have double NAT you don't have to hide stuff.. that is the trouble.. you have a private IP address. Hence it is non routable on the internet.

     

    Some ISP's are cheap.. eg wireless and satellite are particularly bad.. they hand out private IP addresses. It saves them some money.

     

    Is the double NAT all the time.. or only when the connection fails.. ??

     

    Randomly, sometimes once every day, or two, or three, the internet just stops working because of this error.

     

    I doubt the double NAT is causing it.. that is more the result of the poor firmware in the new AC model apple routers and their lack of refinement.

  • steelbom777 Level 1 Level 1 (5 points)

    Thank you for your reply,

     

    It's a Netgear Gateway CG3100.

     

    Ah, my mistake. I thought those were the things I should hide, whoops

     

    We have cable, not wireless or satellite. Our ISP is one of the largest in the country I believe, and we also have the highest tier plan (500GB cap, 100Mbps down) so I don't think they'd be cheaping out on us. (I couldn't say for sure, of course.)

     

    It's only while the connection isn't working. This is basically how it unfolds:

     

    Using internet > stops working > Airport Utility > see "Double NAT" and d/c'd internet > restart AEBS > wait until it starts up> double NAT goes away and now connected again > resume using internet.

     

    I have also suffered this issue with a previous ISP modem and the 4th gen AEBS. I could never fix the issue for some reason. It would just randomly come on, and then I'd just have to let it right itself. I hoped these new models would sort it out.

  • LaPastenague Level 8 Level 8 (42,790 points)

    Very good.. now I know what is happening.

     

    When the modem has a connection drop, (it sounds like you have it bridged), the local interface of the modem passes the internal address of the modem.. until the public IP is restored..

     

    So that is why you get this affect..

     

    Using internet > stops working > Airport Utility > see "Double NAT" and d/c'd internet > restart AEBS > wait until it starts up> double NAT goes away and now connected again > resume using internet.

     

    I doubt the double NAT is the cause of the problem .. it is a symptom of a failed connection from the cable supplier.. (Telstra??)

     

    Because the TC picked up the internal IP of the modem it is now stuck with that address until the dhcp lease expires.. hence why you need to reboot the TC to get back to internet.

     

    I would recommend you go back to using the CG3100 which is a router, in full router mode.. and bridge the TC. Keep track of the daily dropouts in the log.. and just keep hassling the ISP to fix the line. Cable has join issues.. and ISP can get lazy if you still have some internet.. dropouts on cable should be rare.. not daily events.

     

    I have also suffered this issue with a previous ISP modem and the 4th gen AEBS. I could never fix the issue for some reason. It would just randomly come on, and then I'd just have to let it right itself. I hoped these new models would sort it out.

     

    This fact matches the above.. the cause of the problem is not the equipment.. it is the line you are given.

     

    If you actually access the modem interface.. typically 192.168.100.1 or 192.168.1.1 you might be able to turn off the dhcp to the local setup.. this will then cause the error to be no IP instead of double NAT.. but it will restore faster and without your intervention when it returns..

  • steelbom777 Level 1 Level 1 (5 points)

    I see.

     

    Wow, you certainly know your stuff!

     

    Thank you very much. It's great to finally know why. If it annoys me enough I'll do it and complain to BigPond about it.

     

    Again, much appreciated!