bernard.huang
Level 1 (4 points)
Notebooks

Q: Airport Extreme DHCP & NAT settings - can't change NAT's default IPs?

Hi,

 

  I'm trying to setup the airport extreme to be used for our office.

  Our office IP is 10.255.x.x

  When I am trying to setup DHCP & NAT, within the NAT options, there's only 10.0.x.x, 172.16.x.x and 192.168.x.x

 

  How can I get the NAT to have 10.255.x.x?

 

  Without the NAT settings, I can't get this Airport Extreme to assign out valid IP addresses, and therefore useless

MacBook Air, OS X El Capitan (10.11)

Posted on Sep 7, 2016 12:17 AM

by bernard.huang,Solvedanswer
bernard.huang bernard.huang
Level 1 (4 points)
Notebooks
A:

Hi all,

 

  Thank you all for you inputs. But I figured it all out by trial and error.

 

  I really do need DNCP and NAT to be both working. DHCP to provide in actual internet connection, NAT to assign IP address accordingly.

 

  So my setup is "use DHCP" so it automatically assigns an IP address to the Airport Extreme.

  I then have NAT active, set to any of the pre-defined setting. In my case, I put mine as 172.16.1.xxx

 

  When I click on save, the Airport will reboot. After starting up, the Airport will show an error (or warning) saying "Double NAT"

Here's the trick... Right click on the error, and select "Ignore"

The Airport will reboot again, but this time the light turns green, and away we go!

 

  Again, thank you all for replying.

Posted on Sep 10, 2016 12:48 AM

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bernard.huang

Q: Airport Extreme DHCP & NAT settings - can't change NAT's default IPs?

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  • Helpful answers

  • by Bob Timmons,

    Bob Timmons Bob Timmons Sep 7, 2016 6:48 AM in response to bernard.huang
    Level 10 (105,008 points)
    Wireless
    Sep 7, 2016 6:48 AM in response to bernard.huang

    Sorry, but Apple will only allow 10.0.x.x addresses to be assigned by the AirPort Extreme.

  • by tygb ,

    tygb tygb Sep 7, 2016 8:42 AM in response to bernard.huang
    Level 2 (197 points)
    Mac OS X
    Sep 7, 2016 8:42 AM in response to bernard.huang

    Hello !

                Suggested article : AirPort Utility 6.x: Reserve a DHCP address for client computers

    Hope , so it can help you .

     

    Thanks !

  • by Bob Timmons,

    Bob Timmons Bob Timmons Sep 7, 2016 9:02 AM in response to tygb
    Level 10 (105,008 points)
    Wireless
    Sep 7, 2016 9:02 AM in response to tygb

    Unfortunately, the article does not mention that the only IP address range that can be assigned by the AirPort router when it is set up to provide DHCP and NAT service is 10.0.x.x, 192.168.x.x or 172.16.x.x

     

    Confirm by checking the settings in AirPort Utility to see that the "10.0" prefix, or "192.168" or "172.16" cannot be changed.

     

    Screen Shot 2016-09-07 at 10.53.44 AM.png

  • by LaPastenague,Helpful

    LaPastenague LaPastenague Sep 10, 2016 12:41 AM in response to bernard.huang
    Level 9 (52,330 points)
    Wireless
    Sep 10, 2016 12:41 AM in response to bernard.huang

    bernard.huang wrote:

     

    Hi,

     

      I'm trying to setup the airport extreme to be used for our office.

      Our office IP is 10.255.x.x

      When I am trying to setup DHCP & NAT, within the NAT options,

    This is actually easy if you remove NAT.

     

    DHCP is an option. You do not want or need NAT. Then you will have double NAT problems.

     

    So if you want Double NAT..

    The fact that the office uses 10.255.x.x. is irrelevant to devices behind the Extreme.. they may as well be on 192.168.x.x (and I highly recommend you do NOT use 10.x.x.x behind another 10.x.x.x because the Apple router doesn't like routing in that setup.. even if the subnet is correctly class C it works as if it is class A.

     

    In fact if the office is using 10.255.x.x then your Airport could also use a small range in the same IP subnet.

     

    Simply fix the main router to exclude a selection of addresses .. eg 10.255.1.1-200 is used by the main router.. and you can then set the AE statically to 201 and use DHCP on the network tab, to clients behind it from 202 - 254. It works fine as I have it running that way.

     

    Screen Shot 2016-09-08 at 7.52.56 AM.png

     

    Screen Shot 2016-09-08 at 7.53.15 AM.png

  • by Bob Timmons,

    Bob Timmons Bob Timmons Sep 7, 2016 4:18 PM in response to bernard.huang
    Level 10 (105,008 points)
    Wireless
    Sep 7, 2016 4:18 PM in response to bernard.huang

    Your original post stated that......

     

    "When I am trying to setup DHCP & NAT, within the NAT options, there's only 10.0.x.x, 172.16.x.x and 192.168.x.x"


    If you don't need the AirPort to provide NAT service, then LaPastenague has a good idea for you.

  • by bernard.huang,Solvedanswer

    bernard.huang bernard.huang Sep 10, 2016 12:48 AM in response to bernard.huang
    Level 1 (4 points)
    Notebooks
    Sep 10, 2016 12:48 AM in response to bernard.huang

    Hi all,

     

      Thank you all for you inputs. But I figured it all out by trial and error.

     

      I really do need DNCP and NAT to be both working. DHCP to provide in actual internet connection, NAT to assign IP address accordingly.

     

      So my setup is "use DHCP" so it automatically assigns an IP address to the Airport Extreme.

      I then have NAT active, set to any of the pre-defined setting. In my case, I put mine as 172.16.1.xxx

     

      When I click on save, the Airport will reboot. After starting up, the Airport will show an error (or warning) saying "Double NAT"

    Here's the trick... Right click on the error, and select "Ignore"

    The Airport will reboot again, but this time the light turns green, and away we go!

     

      Again, thank you all for replying.

  • by Bob Timmons,

    Bob Timmons Bob Timmons Sep 10, 2016 5:55 AM in response to bernard.huang
    Level 10 (105,008 points)
    Wireless
    Sep 10, 2016 5:55 AM in response to bernard.huang

    Unfortunately, "ignoring" a Double NAT error will not make it go away.

     

    As you know, Double NAT can create some unpredictable problems on a network like slow browsing, (or no browsing to some websites), communication problems with other devices on the network to name a few.

     

    But sometimes, you can get away with the Double NAT on a network, and hopefully that will be case for you.