Airport Extreme - 'internet connection' or 'double NAT'

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Airport Extreme - 'internet connection' or 'double NAT'

My 3 week old Airpot Extreme 802.11n router connected to a D-Link DSL-320T modem seems to work fine all day long. However, randomly, but often after inactivity periods, one of the three scenarios occurs, which stops internet access on my network (LAN and WAN).

1) 'internet connection' error comes up. The modem looks fine, but the AEBS remains blinking orange until restarted, at which point all is well.

2) Green light... but there's no internet connectivity. I can access the modem's web interface, see that it's connected, but can't access the internet until I reboot the AEBS.

3) 'double NAT' this is more rare nowadays - it sort of went away after numerous reboots, again, rebooting the AEBS fixes the problem.

So... is this normal? is my AEBS broken? Should I get another modem?

The AEBS issue affects the whole network - all ethernet & wifi traffic.

(The network was originally fine with a D-Link DIR-635 'n' router, except my MBP kept loosing all network connection whilst claiming to still be connected to the wifi D-Link router... I figured that an Apple router would make my life simpler...)

Airport Extreme 'n' router, Mac OS X (10.5.2)

Posted on Mar 11, 2008 8:30 AM

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Answer 1

lui-g Author

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Mar 20, 2008 4:10 AM in response to lui-g

Disabling IPv6 on both the Airport Extreme nd the Macs didn't work...
Trying out today's new firmware - 7.3.1

Let's see if that fixes things.

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Answer 2

Mar 20, 2008 5:55 AM in response to lui-g

I wouldn't get your hopes up. I've had your problem #1 for almost a year now. After upgrading to 7.3.1 I now get a permanent flashing orange light. Rebooting the AEBS (dozens of times) no longer solves the "No valid IP" issue. Intensely annoying, to say the least.

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Answer 3

lui-g Author

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Mar 26, 2008 2:07 AM in response to Timothy Houghton

hmm - looks like you're right.

The new firmward didn't really change much.

I still have problem #2 (all looks well, but can't actually get to the internet unless I reboot the AEBS...

I'll try Apple tech support, since this box is only just over one month old.

(wish me luck - funnily enough, the only time I had to use Apple tech support was back in late 2000 with a DOA Apple Airport Basestation! 7 years of Apple products without problems, until I buy another Airport...).

In my scenario, a possible solution would be to use the AEBS as just an Ethernet to WiFi bridge, and use my old D-Link router with WiFi off as the DHCP server.

Seems silly though.

I'd be happy to buy another modem, if I knew of one that will play with the AEBS.
(I'm using the D-Link 320T ADSL modem)

I'll report back on my Experience.

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Answer 4

Mar 26, 2008 10:51 AM in response to lui-g

The 7.3.1 update and the possibility of wireless Time Machine has got me to investigate this a bit more. It's starting to look like it is our modems (I'm using the D-Link DSL-300T which is very similar to yours). According to various posts in this support forum http://www.expansys.com/f.aspx?i=110630 our modems crash after intensive activity (p2p etc). And my particular modem has a hidden firewall with NAT which you cannot disable (yours probably does too). Thus the double NAT issue. I have partially confirmed this by turning off the AEBS's NAT (by switching to bridge mode) and running bittorrent with 100s of peers for the last few days and it hasn't failed yet. However this isnt permanent because witching to bridge mode means only one of my wireless devices can have access to the internet at a time. Looks liek the only solution is to get a different adsl modem.

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Answer 5

larksoft

Level 1

5 points

Mar 26, 2008 1:48 PM in response to lui-g

Hi all,

I've been reading these and other posts in trying to track down an intermittent DNS issue with the AE we just got. Previously we had a Netgear 834G acting as ADSL Router, Wifi base station, etc but were getting bad reception to various areas of the house. So an upgrade to 802.11n seemed a good solution and with the Airport we get the functionality of using Airport Express to extend the network (we are already using one to share a printer). We've changed the Netgear to be just a modem and we're running PPPoE from the AE; that part works fine.

I was pretty surprised to find that such an expensive base station as the AE doesn't handle DNS itself; what's worse is that from time to time (at least 3 times since it was installed lastnight) it just stops forwarding DNS requests & seems to require a reboot to fix the problem. The workaround I've implemented for now is to add the OpenDNS servers (208.67.220.220 / 208.67.222.222) to each client Mac's DNS settings (Open network preferences, with the Airport selected, click on Advanced, then DNS). This adds the servers to /etc/resolv.conf and should solve the issue for when the AE next decides to mysteriously stop forwarding DNS requests to the ISP DNS servers I set in its config. It should also be independent of the ISP we use (so that if we change, we don't have to change all the machines in the house) and, since a couple of them are laptops they should also work wherever the laptops go and join other WiFi networks (e.g. my office).

But, it would be nice not to have to mess around with the settings of all the client machines, they should be able to just use the AE as their DNS server IP (as handed to them by DHCP) on an ongoing basis.

Anyone else seen this? I see the latest firmware for the AE doesn't seem to have fixed it either.

AW

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Answer 6

dchao99

Level 4

2,092 points

Mar 26, 2008 3:36 PM in response to Timothy Houghton

"Double NAT" means the AEBS has detected that it's behind a NAT firewall that share the same IP address range as itself.

Since your ISP has given you a private address, that clashes with your AEBS, you can change your IP address range to avoid the conflict.

Go to Internet > DHCP and change the DHCP beginning address.

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Answer 7

dchao99

Level 4

2,092 points

Mar 26, 2008 3:49 PM in response to larksoft

Never has DNS problem. How do you know it has stopped forwarding DNS request? Maybe it's your ISP's DNS has stop responding to requests.

I don't know any home router that will resolve non-authoritative requests. It's not like its an enterprise DNS server that need to serve 100+ users.

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Answer 8

Mar 26, 2008 4:13 PM in response to dchao99

I think you've misunderstood my post. My ISP hasn't given me a private IP address.

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Answer 9

dchao99

Level 4

2,092 points

Mar 26, 2008 5:57 PM in response to Timothy Houghton

So the D-Link has a NAT that can't be disabled, and the D-Link must be dishing out private IP addresses. Thus the "Double NAT". Still, change the DHCP address change on AEBS should avoid the "Double NAT" message. Or just set your AEBS in "Bridge Mode" (both NAT and DHCP off), then there is only one NAT and one DHCP on your subnet.

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Answer 10

Mar 26, 2008 6:18 PM in response to dchao99

You seem to be repeating things I've already written.

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Answer 11

lui-g Author

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Mar 27, 2008 1:49 AM in response to larksoft

Hi,
I didn't think about the DNS, and that coyuld be the problem here.

Whenever the internet goes down next, I'll try to access a known site by IP directly, and see if that works.

Apple support were very good, and are sending me a replacement, to see if that fixes it.

I'm sure we'll get to the bottom of this soon.

the Double NAT and Internet Connection problems have gone since the firmware upgrade. All I get now is problem #2 which stays on the green light, but passes no internet (which could very well be a DNS forwarding issue as pointed out).

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Answer 12

lui-g Author

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Mar 27, 2008 1:57 AM in response to dchao99

The modem has a DHCP that gives 192.168.1.xxx range addresses, and the AEBS uses the 10.0.1.xxx.

Neither is in Bridge mode, as I found that the modem in bridge mode didn't work for the AEBS (flashing orange), and the AEBS in bridge mode looses much of the functionality I want out of it.

The AEBS is set to Ethernet/Using DHCP, and is displaying my true ISP-assigned IP address, and ISP's DNS servers - all of which were obtained automatically (as they were not manually entered on the modem either).

I'll try the new AEBS when it arrives today/tomorrow and report back after the weekend, but right now, either hardware failure or the DNS issue look like the culprits for my problems.

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Answer 13

lui-g Author

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Apr 2, 2008 10:59 AM in response to lui-g

After a support error, whereby I got sent a replacement power cord (with the wrong plug), I did receive the replacement unit.

It has the same problem, indicating that the issue is either the firmware, software settings, or modem incompatibility.

I shall pursue this with Apple tech support, and see if I can get a resolution.

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Answer 14

r15

Level 1

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Apr 16, 2008 8:30 AM in response to lui-g

-bump-

Has anyone had any luck in figuring out the green light but no internet issue? I recently "upgraded" to the AEBS and find that every morning when I start my computer I have to next reboot the AEBS so I can access the internet even though I have a green light on the front of the unit. Once I restart everything works great until the computer goes to sleep or shuts down. I then have to reboot the AEBS again next time I need internet access. Rather odd if you ask me.

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Answer 15

lui-g Author

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Apr 21, 2008 5:34 AM in response to r15

OK, here's an update.
I've had the replacement AEBS for a few weeks now. I get exactly the same intermittent problem.

The 'internet connection' and 'double NAT' problems don't really show up anymore, but I loose internet connection despite the green light remaining on.

When the internet goes, the modem's IP address is sometimes self-assigned, and at other times looks right.

I can't seem to find anything relevant on the AEBS or modem logs.

Looks like there's some incompatibility between the AEBS and the modem, or even the AEBS and my ISP...

Sometimes the internet stays up for a couple of days, other times it goes down numerous times in a day.

Soft-rebooting the basestation (make a change, undo-it, and click 'update') seems to resolve the problem instantly.

Another router I have (also by D-Link) never had any problems...

I will try calling Apple once more to see if they can simply recommend a modem that works, failing that, I'll re-instate the old D-Link router, and just use the AEBS as an overpriced ethernet-to-wifi bridge...

I would definitely NOT recommend one of these unless you KNOW it works with your modem. Also, having to re-boot the base station with every change you make is annoying, as is having to use software rather than a browser to reboot it... (meaning I can't reboot it from the iPod touch when it's gone down at night, or in the morning...)

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