Q: Ethernet has a self-assigned IP address and will not be able to connect...

Hi Ben,

I have the same problem as you on my Brother-in-Law's 24" iMac. I did the same thing you suggested and it shows up the same way so it's likely we have the same issue.

Do you have parallels or VMware installed?

been having the same problem....

and i'm the kind of guy that won't go to sleep until i solve the prob... needless to say i haven't slept for days looking for an answer.

i tried every thing google had to offer. but the answer was so so simple...

turn off DSL, router and comp. and when say turn off i mean un plug from power outlet.

turn on DSL. wait till it is fully on

turn on router. again, wait till it is fully on lights geern and all.

plug in the mac to the power and turn it on. and behold.... you have internet!!!!

for macbooks i recommend unpluging the battary

my system is on DHCP so no need to enter anything for internet but i'm sure it will work for PPPoE as well.

hope this help.

nothing so far works . . . help

why do we have to fix this . . . a $2k brand new imac!!!!!!!!!!!!!!!!!!!!!!

THis happened to me thrice this year (2011), I though its my internet service that has problem but i tried my mac to other service provider and its not working...same problem...ethernet has a self assigned IP address and will not be able to connect...damnED...IS THIS REALLY A MAC OR QUACK!

The only solution for me after trying everything else in this thread was to reset my airport extreme to factory default settings. Everything's now back to normal, i can connect through either airport or ethernet. For now.....

i have exactly the same issue and read all the posts. but nothing works for me. now using snow leapord. do you guys think upgrading to Lion will help.

afterall, is this a hardware or software problem for my imac? FYI, it was perfectly fine before (just bought it for 2 months). but just all out of a sudden, it has the self assigned IP.

Is lion the solution?

thanks much all.

check your isp . . .in my situation they had a gllitch!

Well I was having the same issue. I have a 27" iMac hard wired to an AT&T 2wire router and it works perfect. Sitting right next to it is a 21.5" iMac that is also hard wired to the router. It would occasionally lose the wired connection and jump over to the wireless connection. I would shut off the wireless and the wired wouldn't work. I tried everything, but occasionally I would see a message pop up on this mac (even when the wireless wasn't turned on that said something like "Another device on this network is using the same IP address.....". I have a few airport express's throughout the house that I use to stream music. I found the one in conflict, went into the settings on the airport express and hit restart and the second I hit the button the internet connection on the 21.5" iMac worked with the wireless shut off. It was a miracle!!! I then noticed that when the airport express turned back on, it was assigned a different IP address and things seem to be working great. I saw some other posts that say go into Proxie and turn off passiv ftp, but I didn't need to do that. Once I shut off that airport express, things now work perfect. I would have bet my life the ethernet port was bad.

Thanks Rchapma. I was having the same issue, and it turned out there was another device on my network (a NAS drive) that was sending a conflicting IP address. The solution that worked for me was to pull EVERYTHING off my network -- wired and wireless (phones, iPad, wife's laptop, PlayStation, etc.) then restart the router. The self-assigned IP address immediately corrected itself and I'm back up and running.

For network security purposes, I changed my router IP address to 169.XXX.X.X.  Apparently Apple designates 169 addresses as problematic.  My fix was to assign a different router IP address from 169 and this fixed my issue. 

http://support.apple.com/kb/TS1920

I cannot change by routers IP address because I only experience this problem on school, and 7000 other students are using it - including macbook users- without any problem... help!?

Has anyone tried removing all the RAM and putting in new RAM? We had a PowerMac G5 at work that couldn't connect to the Ethernet no matter what we did. I was convinced it was the motherboard/Ethernet connection failure. But after running a couple of hardware tests, it came up with bad RAM. Put in all new RAM, and lo and behold, we have Internet!!

This would explain why multiple computers can connect to an internet connection, but one computer doesn't.

I'm having this problem with my MacBook Pro right now, and will attempt to take out the RAM when I get home to see if it fixes it. I had it at work, and was in the middle of surfing on our Ethernet network, when it suddenly stopped. I just put new RAM in a few weeks ago, so one might have failed.

OKAY FOLKS here is what worked for me Mac OS X 10.5.8 delete the /Library/Preferences/SystemConfiguration/com.apple.airport.preferences.plist ..... restart magic works again.