Lawrence Haber

Q: Getting occasional Double NAT error msgs

I am connecting to the internet with a Arris TM822 cable modem which then feeds a current model  Airport Extreme. From the APE, I feed two other Airport Extremes via ethernet wires through a Linksys SE1500 switch. In other words, the switch sits between these three APEs. I also distribute signals wirelessly to two Airport Expresses. The structure of the network had been first setup 6 months ago and has run well.

 

On a seemingly random basis, I am now losing internet connectivity. When I access Airport Utility, I am getting double NAT messages. There have been no recent changes to my network that I can think of and the devices feeding off the network has been stable. For a while, I was able to get rid of the double NAT message by either rebooting the modem and the first APE. Sometimes, if I wait, the error message goes away, sometimes not.

 

Most recently, I rebooted the modem and the first APE, isolated from all other devices and then replugged everything in and  an running fine.

 

Question: any idea what the problem is and how I can zero in on the device that is at fault?

 

thanks for your help.

 

Larry

Mac OS X (10.7.3), Pages 4.1

Posted on Sep 11, 2016 11:41 AM

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Q: Getting occasional Double NAT error msgs

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  • by Tesserax,

    Tesserax Tesserax Sep 11, 2016 11:52 AM in response to Lawrence Haber
    Level 9 (54,452 points)
    Wireless
    Sep 11, 2016 11:52 AM in response to Lawrence Haber

    To help in narrowing down which the culprit may be I would suggest that you just leave the modem and the "main" AirPort Extreme powered-on. Leave the other base stations powered-off. Try this configuration for a few days to see if the double NAT issue returns.

     

    Which exact models are your AirPort base stations? How long have you had the Arris modem?

  • by Lawrence Haber,

    Lawrence Haber Lawrence Haber Sep 11, 2016 12:02 PM in response to Tesserax
    Level 1 (9 points)
    Wireless
    Sep 11, 2016 12:02 PM in response to Tesserax

    Thanks.

     

    The APE that connects to the modem is a 802.11ac model. One of the more distant APEs is a 1st gen 802.11n model and the third is also an 802.11ac model.

     

    I've had the modem for at least 3 years.

     

    I have read that occasionally these modems have routers inside them. I've checked the manual best I can, and it does have telephony capacity, which I do not use. Could the double NAT be coming from the APE bouncing off the modem?

     

    Alternatively, could the switch be faulty? Or, could the APEs be conflicting with each other and their attempt to "figure" the network out? APE seem to be smarter than they used to be.

     

    thanks again,

     

    Larry

  • by Tesserax,

    Tesserax Tesserax Sep 11, 2016 12:15 PM in response to Lawrence Haber
    Level 9 (54,452 points)
    Wireless
    Sep 11, 2016 12:15 PM in response to Lawrence Haber

    Thanks for providing the updates.

     

    I pulled up information on the TM822 and, based on what I found, it is a "pure" modem and not a combination modem and router or gateway device. However, modems can still provide a very limited "NAT-like" function which may be the cause of the double NAT errors that you are seeing.

     

    The reason to just have the modem and the first Extreme running is to rule out either being the issue before we tackle adding back in the other networking components.

     

    In the mean time the Ethernet switch should not be an issue, but potentially one of the other base stations may be.

     

    It looks like you have a basis for a roaming type network with each of the base station interconnected by Ethernet. Is this the way you have your network configured now?

  • by Lawrence Haber,

    Lawrence Haber Lawrence Haber Sep 11, 2016 12:24 PM in response to Tesserax
    Level 1 (9 points)
    Wireless
    Sep 11, 2016 12:24 PM in response to Tesserax

    Thanks. I will try that.

     

    I might have a roaming type network, but not positive. The support doc on roaming networks, persumes that the router extensions are directly connected. Mine are not, there is the switch in the middle.

     

    When I set this up, I plugged the first APE into the modem and set it up. I then plugged in the extended APEs and let Apple make the connection, the software saw a wired connection and completed the setup essentially automatically.

     

    thanks again for your help, it's very much appreciated,

     

    Larry

  • by Tesserax,

    Tesserax Tesserax Sep 11, 2016 12:34 PM in response to Lawrence Haber
    Level 9 (54,452 points)
    Wireless
    Sep 11, 2016 12:34 PM in response to Lawrence Haber

    Unfortunately, the linked document is a bit outdated. Not sure when Apple will get around to update it.

     

    The "direct" connections are also a bit misleading. As long as each of the base stations are reachable by Ethernet to the "main" base station you should be good to go. FWIW, in my network setup, I use a Cisco router as my "main" router. That is connected to a Ethernet distribution panel that feeds Ethernet to different rooms in my home. At a number of locations, I have AirPort base stations connected to Ethernet wall jacks.

     

    It looks like the AirPort Utility did its job correctly by identifying that the base stations are connected by Ethernet. Again, the set up may be fine.

     

    The important keys for a roaming network are:

    • All base station must be interconnected by Ethernet ... or powerline adapters providing Ethernet using your home's electrical circuit.
    • Each base station must have a unique base station name.
    • Each base station must be configured to "Create a wireless network."
    • Each base station's wireless network must use the same network name and use the same wireless security type and password.
  • by Lawrence Haber,

    Lawrence Haber Lawrence Haber Sep 11, 2016 12:41 PM in response to Tesserax
    Level 1 (9 points)
    Wireless
    Sep 11, 2016 12:41 PM in response to Tesserax

    All that is true in my case.

     

    I will try running without everything and than selectively reinstating and see where that gets me.

     

    Many thanks again.