Ethernet MAC address has changed and I can no longer connect to the network

How are people getting on with this problem? I was definitely seeing this, but just opened up two reserved slots on my router (one for the real address, one for the 00:10:18 one) so didn't really care.

Since the latest software update, however, 5 out of the last 7 times I've started my iMac it's claimed to not have an Ethernet card at all. (System Profiler says 'No Ethernet cards installed')

On the occasions it has booted up with the ethernet card, it has come up with the correct address. I'm wondering whether they've tried to fix this in the latest update but instead it now loses the card completely where before it would have just had the 00:10:18 address.

Has anyone who was seeing the original problem now seen that their ethernet card just disappears from the system from time to time?

Conversely, after the update does anyone still see their card switch to 00:10:18, but otherwise work fine? (i.e. it's probably that my ethernet card is suffering hardware failure and nothing to do with the software update :-( )

(For reference, I'm seeing this on a mid-2010 27" iMac)

Many thanks for any pointers either way.

Later edit:-

Further searching shows that other people are suffering the same issue:-

https://discussions.apple.com/thread/3140081?answerId=15532854022#15532854022 (and others)

so it looks like my supposition might be correct.

If you've seen the 00:10:18 problem, best not to do a Software Update to 10.6.8 for the time being...

I'll post here if I ever find a solution.

Hi there - two of our macs (one iMac11,2, the other iMac11,3) have this same issue, both feature the BCM5701 chipset, and messages such as shown below are in the kernel.log:

kernel[0]: BCM5701Enet: Ethernet address 00:10:18:00:00:00

I'm currently working with an Apple engineer to get this resolved, however I'd be particularly interested to hear if anyone else is facing this problem, and if a logic board replacement (with original OSX install) has made the problem go away permanently.

Please post here, any stories of issues/replacements/resolutions will help to further a long term solution.

Cheers.

greetings, in my case my iMac is being booted off my corporate LAN due to sending a 'fake' MAC address after the update to OS X 10.7 Lion.

My kernel.log shows what might be a simple fault?

Jul 27 12:44:13 localhost kernel[0]: AppleYukon2: Marvell Yukon Gigabit Adapter 88E8055 Singleport Copper SA
Jul 27 12:44:13 localhost kernel[0]: AppleYukon2: RxRingSize <= 1024, TxRingSize 256, RX_MAX_LE 1024, TX_MAX_LE 768, ST_MAX_LE 3328

Jul 27 12:44:17 localhost kernel[0]: yukon: Ethernet address 00:1b:63:b5:xx:xx
Jul 27 12:47:43 TVA36218 kernel[0]: Ethernet [AppleYukon2]: Link up on en0, 1-Gigabit, Full-duplex, Asymmetric Receiving flow-control, Debug [796d,ad08,0de1,0200,c9e1,2800]

Jul 27 12:47:46 TVA36218 kernel[0]: AppleYukon2 - en0 link down

my 'fake' MAC address is 00:00:04:00:00 so is slightly different from the Broadcom issue of 00:10:etc

I wonder if it is as simple that sometimes my NIC is referred to as "AppleYukon2" and othertimes (when setting the actual address) as "yukon" lowercase.

Message was edited by: David.Shaw to mention that it's an iMac7,1 core2duo 2GHz 4GB 250GB HDD

I'll have to give that a shot next time. I just finally got mine up and running after about an hour of rebooting, checking cables, and attempted diagnostics.

two years later ... actually, this issue has all but disappeared - every time it did occur, I ran the bit of code , shut down and restarted and was able to work, but I have not had to do that for months now .. touch wood .. so either they repaired the issue in some update or it just went away ???

well - two years and two months and it re-occurred one sunny Sunday and I needed two restarts with the bit of code, and now iTunes and the iPod are not cooperating properly any more - maybe unrelated, maybe not