Ethernet on iMac stops working

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Level 1

5 points

Ethernet on iMac stops working

My iMac is connected to a FritzBox (Cable modem and router in one) via ethernet.

Reproducibly, the internet connection dies after a few minutes. The ethernet configuration either shows all normal status or, switches to IP 169.254.8.36, subnet mask 255.5.0.0.

Refreshing the DHCP lease, removing the ethernet cable and plugging it back in, removing the ethernet adpater from the system panel and adding it back, switching to hardcoded IP, clearing PRAM/NVRAM, using a differnet cable, using a different router: no change. Only rebooting the Mac helps to make the connection work again but it'll die over and over again.

Over Wifi, all is working fine but I cannot use "Wake on Lan", so that is not an option.

My config is: iMac 27" mid 2012, 16GB RAM, Core i7 3.4 GHz, Mac OS X 10.8.3

Is there a known problem with the ethernet port on the iMac?

I'm tempted to reinstall but I don't know if that's a good idea or just wasted time.

Any opinions or similar issues anybody?

iMac, OS X Mountain Lion (10.8.3)

Posted on May 20, 2013 11:30 AM

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Answer 1

BDAqua

Level 10

250,259 points

May 20, 2013 2:10 PM in response to Krumelur76

Hello,

Make a New Location, Using network locations in Mac OS X ...

http://support.apple.com/kb/HT2712

10.5, 10.6, 10.7 & 10.8…

System Preferences>Network, top of window>Locations>Edit Locations, little plus icon, give it a name.

10.5.x/10.6.x/10.7.x instructions...

System Preferences>Network, click on the little gear at the bottom next to the + & - icons, (unlock lock first if locked), choose Set Service Order.

The interface that connects to the Internet should be dragged to the top of the list.

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Answer 2

Krumelur76 Author

Level 1

5 points

May 21, 2013 9:53 AM in response to BDAqua

Um, why would creating another location help me?

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Answer 3

BDAqua

Level 10

250,259 points

May 21, 2013 2:33 PM in response to Krumelur76

It may not, but there are many, many files in different locations used for any particular Location/connection, it's an easy way to test if any of those files might be bad or conflicting. 🙂

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Answer 4

Sep 28, 2013 10:24 AM in response to Krumelur76

Hi Krumelur76, I have exactly the same problem. Even re-installing the OS does not help.

Did you get to a solution?

Thanks,

Reinier

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Answer 5

Krumelur76 Author

Level 1

5 points

Sep 28, 2013 11:49 AM in response to reinierbruil

No solution. I switched over to WiFi. Of course I also reinstalled meanwhile. Same problem. I also bought a USB Ethernet Adapter (Apple original): that works! So it is a hardware issue. However with the USB Eterhnet, Wake On Lan does not work.

So my last option was to use Wifi. But Wake on Wlan only works with AirPort Stations. So I bought a Time Capsule AirPort Station. Unfortunately, not everything that has Apple written on it is good. Meaning: Wake on Wlan does not work reliably.

So I disabled hibernation and only let MacOS switch off HDD and monitor.

I'm now waiting for the next generation of iMacs and then I will buy a new one.

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Answer 6

Sep 28, 2013 12:27 PM in response to Krumelur76

It might not be a hardware issue, try making a new user and testing it in there, if you have the same problem in a new user its hardware and if you dont have the same issue its software

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Answer 7

Krumelur76 Author

Level 1

5 points

Sep 28, 2013 12:30 PM in response to robertnb1986

I reinstalled from scrach. How much newer can a user be? In addition the problem occurs for other user accounts.

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Answer 8

Oct 26, 2013 1:39 AM in response to Krumelur76

This week I had Maverick installed, and until now my wired ethernet connections seems to be in good shape.

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Answer 9

Oct 29, 2013 6:03 PM in response to reinierbruil

I have to now go to my network, which has switched over to wifi by itself. I need to reconfigure the network for dsl. I also need to create a new destination. Then I have to go back and change the destination back to automatic and save all the changes. Then I need to restart my modem/router and if I am lucky it will then recognize my ethernet connection. I have an old lap top which I used an ethernet cabel plugged into the same slot as I previously used for my Imac. The modem instanlty recognizes the dsl connecition on the lap top. Once I do connect to the ISP on the Imac the ethernet connection stays active until the next restart or startup. Modem is OK. Imac hardware OK. Mavericks created all my aggravation. There are other issues on Mavericks that I can correct. It wasn't ready for release. Apple suggested that I replace the modem and the logic board. I don't think so. It is most probably the new operating system. They just haven't admitted that yet. Read the community on Mavericks and you decide.

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