Ethernet not connected - cable unplugged

Question

Ethernet not connected - cable unplugged

27" iMac, 10.6.3, all software and firmware updates installed.

Without getting into too much detail let's say I tested everything from the router to the switch to the cables, mixing and matching everything until reaching the conclusion that it's the iMac. This is a network I built and configured myself, so I know it quite well. Last test was connecting my 15" MBP to the same cat6 cable the iMac cannot detect, which my MBP detects and works with without a hitch.

I've reset the SMC, rebuilt permissions, re-installed OS X, reset pram. I've restarted pressing "v" for a hardware test both with the OS X install DVD in the drive and out but nothing happens. Not sure if anything is suppose to happen...

Wifi works fine but is unacceptable to transfer various gigabyte size files for which I need the Gigabit network

If the ethernet port were dead would it still show up in the system profiler? (it does)

I'm really struggling here.... any more ideas?

MacBook Pro Core2Duo 2.8 GHz, Mac OS X (10.6.3), 4 GB RAM, 500 GB HD

Posted on Apr 27, 2010 7:55 AM

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Answer 1

Dah•veed

Level 9

64,651 points

Apr 27, 2010 8:45 AM in response to Martim Weinstein

To get the Hardware Test, at least on my Macs, you (re)start the Mac, quickly insert the Install DVD and press & hold the D key. I am not aware of the V key alone doing anything at startup. V + Command starts in Verbose mode.

Is Ethernet configured properly in System Preferences/Network/Ethernet/Advanced/Ethernet?

Dah•veed

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Answer 2

Apr 27, 2010 11:59 AM in response to Dah•veed

My mistake. I pressed D, not V. I did it again just in case and can confirm nothing happens. What is suppose to happen? It opens an application?

1 thing I didn't mention is that Ethernet has been working fine for the few months that I've had the iMac. All of a sudden I didn't have internet and as I investigated why, I found the error message on the network prefs.

I've tried a few different settings in the advanced -> Ethernet to no avail, but it's always been on automatic even when it was working.

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Answer 3

xtech

Level 1

30 points

May 3, 2010 9:38 PM in response to Martim Weinstein

Could be a faulty ethernet jack ... although I would reboot first in safe mode/boot to confirm using
half-split search technique we use as certified techs. Follow these steps to confirm the jack is ok
and not a software related issue first.

Instructions: http://support.apple.com/kb/ht1455

This will save some time before next troubleshooting step(s).

"Real sites are for the web and blogs are for frogs!"

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Answer 4

May 4, 2010 2:02 AM in response to xtech

Rebooted in safe mode, removed and replugged the cable, removed the ethernet interface in the network sys prefs and then added it again. It continues to say: No connection: cable unplugged.

Looking forward to the next steps...

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Answer 5

xtech

Level 1

30 points

May 4, 2010 8:28 AM in response to Martim Weinstein

Next step is to check your cable .. it could be a cross-over cable .. grab another one if you have one before we can point to a faulty or damaged Eth-jack.

27 incher hey ... humm I see you did quite a few steps already which might have been a bit of an overkill to the system. How many items do you see in your network settings? ,,, ethernet, airport, b tooth, f wire, VPN, etc.

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Answer 6

May 4, 2010 8:38 AM in response to xtech

Cables have been exchanged and retested on a different machine. No cables work on the iMac, all cables work on my MBP. No wall ethernet plug works on the iMac, all work on the MBP. I've tried and tested everything all the way back into the switch, mixing and matching to eliminate faults... trust me. It's either software or hardware on the iMac. All else is well.

Right now all I have in the network panel is airport and ethernet. I've tried with only ethernet (doesn't work even after restarting). Airport alone or airport+ethernet works fine, as it goes to get it's connection on the airport side. Keep those ideas coming! 🙂

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Answer 7

May 10, 2010 9:44 PM in response to Martim Weinstein

My mom had this same problem yesterday and it turned out one of the wires was bent in the ethernet port on the back of the iMac. Dumb, I know, but it's worth a shot.

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Answer 8

May 11, 2010 4:23 AM in response to ChuckMoser

Thanks, but all wires are straight. I think I'll be taking it in to the shop, was trying to avoid that since it's an office computer. 😟

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Answer 9

panda_po

Level 1

0 points

Jun 16, 2010 11:38 PM in response to Martim Weinstein

Hi,

Have your problem been resolved? My kid has an iMac, same generation as yours, same 10.6.3, and same problem as yours. I checked the iMac's port and wires are straight. I suspect the fault is at iMac. I have no problem with my MBP, using the same ethernet cable, plugged to the same switch.

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Answer 10

JFlynn12

Level 1

4 points

Jun 21, 2010 4:03 PM in response to panda_po

My 27" iMac started to experience similar issues. On reboot, the ethernet port dies and doesn't come back up.

If I unplug and plug the ethernet cable in a couple of times, the port lights up and comes back on line.

The simple explanation is a cable or port issue. But neither is the case. I have unplugged the cable on the iMac and Time Capsule sides -- same result. I have tried three different cables and different ports on the time capsule. Same result.

Very strange problem. I was shocked that unplugging and plugging the cable back in could fix it.

May be time to call Apple.

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Answer 11

R Jones

Level 1

0 points

Jun 26, 2010 7:33 PM in response to JFlynn12

Same problem here. Woke the iMac up yesterday afternoon and no internet. Get the "cable unplugged". Did all the troubleshooting/checking and can't get it working. However my Windows pc works fine on the same network/cable. Either jack is dead or software issue. Apple will be calling Monday. If it gets rssolved, I will post the solution that worked for me. If it doesn't get resolved I guess it'll go to the shop.

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