Ethernet Connection has Stopped Working on Early 2008 iMac

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Ethernet Connection has Stopped Working on Early 2008 iMac

I am running OS X Yosemite 10.0.4 on an early 2008 iMac (20"), Intel Core 2 Duo. Without ever having changed so much as the volume setting for almost a year, my Ethernet connection is no longer working. I'm going mad looking for a way to remedy the situation.

Here are all of the suggested fixes I have tried so far:

I have cycled my router - on several occasions
I have swapped cables - twice
I did a fresh install of Yosemite
I have attempted to run suggested SUDO commands in Terminal at startup
I have reset the PRAM, reset the SMC, and reset the NVRAM
I have changed my DNS to Open DNS
I have erased old locations and created new ones
I have renewed the DHCP License
I have cleaned the Ethernet port
I have deleted the Ethernet network and added a new one
I have tried reconfiguring the hardware settings in network preferences

For added frustration, my Bluray is hardwired to the network and connects just fine, and WiFi still works, even on the troubled iMac. My ISP has reset my router three times to no avail. I am at my wits-end right now and would really like some help here. Does anyone have advice? Troubleshooting suggestions?

Thank you in advance for your help.

iMac, OS X Yosemite (10.10.4)

Posted on Aug 3, 2015 1:15 PM

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Answer 1

Kappy

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Aug 3, 2015 1:19 PM in response to aaroncaine

If all your Ethernet connected devices don't work when you connect them directly to the computer, then the problem is on the motherboard.

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Answer 2

rkaufmann87

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Aug 3, 2015 1:23 PM in response to aaroncaine

It could also be the router, have you tried another one, they can and do fail.

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Answer 3

aaroncaine Author

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Aug 3, 2015 1:22 PM in response to Kappy

What would cause such an issue and how can I troubleshoot/fix it?

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Answer 4

rkaufmann87

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Aug 3, 2015 1:24 PM in response to aaroncaine

If Kappy is correct the only solution is a new main logic board. Ethernet ports are hard connected to the main logic board, that is why I suggest another router.

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Answer 5

aaroncaine Author

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Aug 3, 2015 1:25 PM in response to rkaufmann87

The same connection, and cable, worked fine when plugged into my work PC. The issue has something to do with the iMac.

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Answer 6

Kappy

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361,741 points

Aug 3, 2015 1:26 PM in response to aaroncaine

Chips fail. You can't do a thing about because the entire motherboard needs to be replaced assuming that is the problem. You would need to take it in for service and get a diagnosis to determine if the motherboard is at fault.

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Answer 7

rkaufmann87

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140,418 points

Aug 3, 2015 1:33 PM in response to aaroncaine

aaroncaine wrote:

The same connection, and cable, worked fine when plugged into my work PC. The issue has something to do with the iMac.

Okay, I get your logic but replacing a router is MUCH less expensive than a main logic board.

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Answer 8

Aug 3, 2015 1:35 PM in response to aaroncaine

A few things to try before going the repair shop route:

System Preferences>Network

Click the Assist Me button.

In the next window that pops up, click the Diagnostic button & do the necessary. Post the results.

Ethernet troubleshooting

Trash the following plist files by going to Macintosh HD>Library>Preferences>SystemConfiguration

com.apple.airport.preferences

preferences

NetworkInterfaces

Repair permissions & restart the computer.

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Answer 9

aaroncaine Author

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Aug 3, 2015 2:04 PM in response to Baby-Boomer-USofA

So I did as suggested, including the deletion of plist files and repairing permissions. Still not recognizing the cable as connected. Here's the diagnostics results.

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Answer 10

Aug 3, 2015 4:04 PM in response to aaroncaine

Looks like it's time to take your iMac in for repairs.

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