iphone connect to wifi but DNS doesn't work

Question

iphone connect to wifi but DNS doesn't work

I have just changed my mobile phone from Android(Nexus S) to iPhone 4S. The user experiences of iphone 4S is great as expected. But, but recently I have met the "popular" problem of iPhone 4S. This happens to my new iphone 4S frequently and some time it happens to my iPad 2 as well.

The problem is that, sometime, even you see the iphone has been connected to the WiFi, you can't visit any website unless you type the IP address in the browser. Even you disconnect from the router and use 3G, you still have the problem. The only work around is to restart your iphone.

First I think it is due to the DNS service down from the router. But my other devices and computer have no problem. And I also changed the DNS server address in the iphone and the problem still exists. Even I use VPN, iphone seems not being able to parse the URL to the ip address.

So, my conclusion is that, the DNS process of my iphone crashes. Maybe due to the compatibility of the router. But I think it is more or less the bug of the iphone.

And also,some reports from the internet shows that some user have the problem by installing certain app from app store. So I think maybe it is due to some APIs related with network cause the process crash. It is also may be the scenario of mine because I just started to install a lot of applications on my iphone.

By the way, my iphone is not jail break. So I hope Apple could fix this problem officially as soon as possible. Will them?

iPhone 4S, iOS 5.0.1

Posted on Feb 17, 2012 11:19 PM

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Answer 1

jPhone7

Level 1

51 points

Mar 22, 2012 1:28 AM in response to Jean-Stephane Lee

Okay, this morning it happened again. I unplugged my iphone, surfed some pages fine. Five minutes later I woke it up again, tried to go to the app store. Nothing.

Tried to surf some newspaper sites. Nothing. So I used an IP address rather than the www.blablabla.com address and it works.

Confirmed. Some sort of cirumstances let the DNS service crash. Only IP addresses work. After a reboot (that's the only chance) it works again.

Network reset, restore iOS, all other typical help steps, never cured it.

That's a bug.

Lets put it on http://www.apple.com/feedback/

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Answer 2

Feb 22, 2012 9:12 PM in response to Jean-Stephane Lee

I have resolved the problem by myself. I just figured out that the problem due to the DNS transfer function in my router. If I set the iPhone 4S to use the DNS server as 192.168.1.1 which is also the ip address of my router it will have the problem until I set the DNS to some common DNS service, such as 8.8.8.8 from Google. I think it is the problem of compatibiliy between the iOS and the router.

By the way, the DNS transferring works fine in my router as my Mac, android phone and another iphone 4 has no problem.

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Answer 3

jPhone7

Level 1

51 points

Mar 18, 2012 12:33 PM in response to Jean-Stephane Lee

That is very interesting. I face a very similar issue with my iPhone 4s and iPad since iOS 5.X.

And it is always when I was connected to my home dsl wifi router. It never happened on 3G only or in other wifi networks so far. Its very rarely. But annoying enough.

All other connected devices to that router including apple TV have no such issue.

Next time it happens, I will try using an IP address, rather than a "normal" URL.

Thanks.

j.

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Answer 4

jPhone7

Level 1

51 points

Mar 18, 2012 12:42 PM in response to jPhone7

Forgot to mention it happens on my iPad 1 too. Even after a clean restore of the iPad. No new apps installed, but iTunes Match activated, like on iPhone 4S. just after using match, downloading music, had some download issues, later it happened again. But DNS service down would really make sense. Will let you know.

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Answer 5

jPhone7

Level 1

51 points

Mar 23, 2012 1:35 AM in response to jPhone7

I tried using real DNS addresses in the iDevice network settings, rather than the router address. Unfortunately it happend again. I did a router reset now and usually it works than for a couple of weeks. Sometimes it happens once a months, sometimes twice a day. I wish we could re-start the DNS service or flush the DNS without having to turn off/on the iDevice.

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Answer 6

Mar 23, 2012 1:45 AM in response to jPhone7

I set the DNS server to the public server 8.8.8.8 and the problem has never come back. Now I have upgraded my iphone to iOS5.1 and I think it is stable now.

If you are still having the problem, I suggest you go to the setting of wifi to check if you are using DHCP or static IP address. You have to use the static IP address and manually set everything including using the real DNS server under the problematic router.

unfortunately, when the DNS service of iOS is down, there is no other way than to restart the iDevice.

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Answer 7

jPhone7

Level 1

51 points

Mar 23, 2012 3:24 AM in response to Jean-Stephane Lee

Thanks JS.

I was on static IP and did use the public DNS of my DSL provider which my WIFI router connects to. I'm actually on iOS 5.1 and sorry to tell, that it happened twice yesterday.

I suspect the Google Latitude app and/or iTunes Match or the combination of them that sometimes the DNS service fails. A wrote an Apple feedback on that. Maybe someday it'll disappear with another update. Thanks!

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