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Resolved Question

iMac won't connect to internet anymore using wireless

Aug 13, 2012 6:58PM PDT

Hi,

Yesterday evenining I was suddenly unable to connect to the internet anymore using my wireless connection on my iMac. It says it's connected to the wireless network and it's sends through a correct IP-address but when I try to visit a webpage using Google Chrome or any other browser it says the DNS-lookup has failed, every other application that requires a working internet connection on my iMac also can't connect to the internet.

My iPod Touch can connect to the internet using my wireless connection just fine. I just hooked my iMac up to the network using an ethernet cable and now it seems I'm able to make a connection without a problem, however this is not a permanent solution. I'm using Mac OS X version 10.6.8 any ideas?

Thanks in advance.

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Romands has chosen the best answer to their question. View answer

Best Answer

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iMac won't connect to internet anymore using wireless
Aug 18, 2012 2:22AM PDT

I had a very similar problem recently with my trusty Mac Powerbook G4. After trying many different methods to re-establish internet connection, I set it aside for several days. Unplugged, the (original) battery ran down to zero. I assume one could achieve the same result by removing the battery for a short period. Good news is, that when I plugged it in to recharge the battery, it began working normally.

I don't know if something like this will work with an iMac, but it's certainly worth a try...

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No need
Aug 18, 2012 4:48PM PDT

No need it's already fixed but thanks for the suggestion.

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Please share what exactly the problem was and
Aug 18, 2012 11:39PM PDT

how it was fixed.

I'm sure we would all like to know


P

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Nothing
Aug 19, 2012 4:10AM PDT

The problem was my iMac and my iMac alone was not able to make a connection to the internet using Wi-Fi. I had an ip address subnet mask, router address etc. Tried the usual, unplugging network devices, rebooting computer, renewing DHCP-lease and so on but nothing seemed to work.

It was like that for a couple of days then it just began working again with my current setup like it has been working these past couple years. No clue why. I've never had problems before with my Wi-Fi.

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Answer
Have you tried
Aug 14, 2012 12:19AM PDT

Have you tried going into the network settings, then the settings for the specific connection, and renewing the DHCP lease?

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Yep
Aug 14, 2012 12:51AM PDT

Yep, it just renews it and ip address subnet mask and router numbers show up seemingly normal. I just don't understand why my internet connection seems fine one moment and is gone the next while every other device using the same wireless connection works fine...

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Answer
Is it a secure WPA2 AES personal WiFi?
Aug 14, 2012 12:57AM PDT

I don't want to bore you with why just one system can get knocked down with those kid friendly hack tools. So try a secure WiFi and don't hide the SSID.
Bob

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It's secure
Aug 14, 2012 1:07AM PDT

Yes, it's secured with WPA2 and the password itself is also very complex so I don't think it's very likely that my WiFI got hacked. The SSID is also not hidden so I don't think that's part of the problem either.

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It was worth checking.
Aug 14, 2012 1:45AM PDT

The password complexity does not make it more secure. I'd rather not bore you why that is. But there can be issues with complex passwords that include non-alphanumerics.

In other words, stick to a-z, 0-9, A-Z for the passwords. Yes, that's a bug or limitation in some driver or such but rather than tilt at windmills you work with the system.
Bob

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Ok
Aug 14, 2012 1:59AM PDT

Ok, thanks for the tip but my password doesn't contain any non-alphanumerics anyway since I indeed had some problems connecting some devices to my WiFi using non-alphanumerics.

Does anyone else have a clue for what could be causing this problem?

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Since the DNS failed.
Aug 14, 2012 5:08AM PDT
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Seems clean
Aug 14, 2012 5:31AM PDT

I used this tool to check for Flashback and it came up clean then I used the terminal command in this article and it too came up clean. I also have Sophos Anti-Virus installed which I used to scan my computer, again nothing so I guess it's not a trojan or malware of some sort. Just doing some random Google searches now, lots of DNS problems but none specific to my situation so far.
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Answer
Any possibility there is a router/WiFi information that can
Aug 14, 2012 6:32AM PDT

Any sharing about the router would be helpful. For example some routers have limits on how many machines can connect. As the router is not mentioned, I can't look to see if that is a factor here.
Bob

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Answer
Here'a a test.
Aug 14, 2012 11:10AM PDT

Let's not use the DNS.

http://74.125.224.224/ should get you to google.com. If this is a DNS issue that may shed some light on this but as the details are so slim after all these posts I don't know what else to do but change hardware or reload the OS.

For example you could have shared the wifi connection details IP, netmask, default route, DNS entries. But some won't do that or can't. This means suggestion move to hardware or reloading the OS.
Bob

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Connection details
Aug 14, 2012 6:40PM PDT

Nope, it won't connect to google.com using the link you gave me either. I'll give you a rundown of my network setup maybe that'll help. My modem is a Motorola SBV5121E which is connected to a D-Link DES-1005D which is in turn connected to a D-Link DWL-G700AP Wireless Access Point.

The IP I'm currently getting on my iMac from my wireless network is 78.21... and another three digits. (don't know how safe it is to post your entire ip address on the internet)
My subnet mask is 255.255.248.0.
My router is 78.21.0.1

I've changed my DNS servers to those from Google, I've also tried the OpenDNS servers, still same result.

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Correction
Aug 14, 2012 6:43PM PDT

Correction on the last post just to be clear the D-Link DES-1005D is an ethernet switch.

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Excuse the butting in here,
Aug 14, 2012 9:37PM PDT

but if you have a router in this network, then all your machines should be getting an IP address of 192.168.x.x
and not the 78.21.x.x

That number would indicate that only one computer at a time can use the internet as it is a derivative of the number that the modem has.

Even if the router were integrated with the modem, common in DSL connections, everything downstream of the modem would be getting their IP addresses from it which would result in a 192.168.x.x number.

Is this a Modem/Router combo or is there a standalone Router somewhere that was not mentioned?

P

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Not that I know of
Aug 14, 2012 10:17PM PDT

There's another modem that I had not mentioned but I believe that one's used for my digital tv box since there seems to be no direct connection between that modem and the rest of my network, it just has one cable in it that goes straight up to the living room. So there doesn't seem to be a router of any sort in my network.

But then the question remains why did everything work simultaneously before and did my iMac and my iMac alone all of a sudden decide not to connect to the internet anymore?

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Update
Aug 14, 2012 11:13PM PDT

Update: apparently my internet provider itself works as a DHCP server, giving out IP adresses through my modem to my different devices, that would explain why I can connect various devices simultaneously without having a router. Still doesn't explain why I can't connect my iMac though. Maybe it's a hardware/software failure?

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OK, but,
Aug 15, 2012 12:09AM PDT

unless you have a service other than the normal residential service, you would normally only have the one, prone to change, IP address going to the house.

78.21.x.x is an "outside" IP address which is given to you by your ISP. Your Router, which may be inside your Modem, supplies an "inside" IP address (192.168.x.x) to all the devices connected to your internal network and connects the two networks together. (inside to outside)

Some cable modems, notably Motorola, will act as a DHCP server when they are disconnected from the incoming cable and your devices are first connected and booted up. (it assigns 192.168.x.x addresses to those devices)
While this works quite well, it is no substitute for a dedicated Router.

Who is your provider?
Cable or DSL?
Normal Residential or Business?

P

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My provider is
Aug 15, 2012 12:27AM PDT

My provider is Telenet (I live in Belgium). Both my modems are cable and it's a normal residential connection. I do however know for a fact that my provider works as a DHCP server cause it's written in the manual and on their website. Like I said this has worked before with the same configuration for over 2 years so I don't see why these problems would suddenly come up now. Maybe they changed the maximum number of ip adresses assigned per user but I'd have to check with my provider for that.

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Actually it does.
Aug 15, 2012 12:22AM PDT

Many ISP's lock IP''s to MAC (not to be confused with Mac) Addresses so all this discussion so far was a waste of time.

It's a shame I didn't get the network upfront.

It is not a hardware failure in my view. It's a network in need of setup.

Such as the usual.

ISP's Modem -> Router -> other things.

Anything else and you find you become a network Guru.
Bob

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OK
Aug 15, 2012 12:52AM PDT

Ok, since my network seems to be the problem, I'll just contact my provider to see if they can adjust/reconfigure my network. Thanks a lot for the amount of answers/help!

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Wireless connection falls out
Aug 17, 2012 11:38PM PDT

I don't know if there could be any connection,but for years now with T-Online router modems our Apple Machines have tended to lose the connection between Airport and the router modem. When it happens, it happens to all Mac computers with a wireless connection to that router.There is only one answer and that is simply to turn off the T-Online equipment and turn it back on again. The wireless connection re-establishes in about a minute. This happens about every other day.

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Stop using the Airport as a Router
Aug 18, 2012 12:02AM PDT

and configure it to only pass traffic from the T-Online Modem/Router.

I suspect that you have two DHCP servers running on your home network. Devices connected wirelessly to the Airport probably have an IP address of 10.x.x.x while those connected directly to the Router/Modem have an IP address of 192.x.x.x

P