Ethernet port not working

My iMac lost the ethernet port a few days ago. Since it was the second time in 2 months I have had a connectivity problem I took it to the Apple store. They diagnosed it as a bad Logic (mother) board.

I have this same issue and I typed in netstat -I en0 as you earlier suggested which resulted in:

Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll

en0 1500 <Link#4> 583 0 1302 0 0

I have heard that this isue can be created through "Link Aggregation" and can be solved by breaking a bond to delete corruptive packets. Is this my computer telling me that this is what is going on? Please help! Thank you.

I had this crop up today on my 2008 24" iMac. I simply deleted the previous Ethernet settings in Network settings, added a new setting, hit "apply" and I'm back in business. I hope I don't see this again but it seems to be working fine now and even appears faster. Go figure.

I have the same problem with the iMac, ethernet used to work but now not working and wifi is fine.

Has anyone tried a ethernet to USB adapter ?

I'm running 10.6.8 on an early intel iMac and after an update in Aug/Sep 2013, my internet connection via ethernet to a dsl router was slow so I decided to reset everything. After that, no internet, just a red status with disconnected notice. I knew the ethernet still worked because when I plugged it into my Win7 netbook, I had internet in less than a minute (and I turned off all wifi).

Here's what I did to fix the problem on my iMac:

With the ethernet cable installed...

I deleted all my networks.

I chose to add a network, ethernet of course.

I got the same not connected/not working notice with the red indicator. Dispair.

Out of curiosity or desperation, I clicked the "Advanced" button.

I saw the configuration set to 'Automatic,' so I changed it to 'manual'

The status indicator went to yellow and then in a few seconds it went green.

The computer connected itself, and it is back to the original connection speed.

here is what i did, The drivers for the network cards seem to have an issue with a buffer overflow apparently, changing the hardware configs in advanced brought it back alive in seconds. here is a link to the video that explains what to do

http://www.youtube.com/watch?v=u1P6X87qArs

I just recieved my iMac (27"/2013) a couple days ago. After the inital setup access to network drives/printers and the Internet worked without issue until I updated to OS X to 10.9.1 (it was actually the first thing I did once I got to the desktop).

After the update and reboot, I could only connect via WiFi; my ethernet connection would not pull DHCP or access the network even if I set a manual IP address. I read through a couple of similiar posting without any resolution to the issue.

At one of those 'try anything' moments, I started making various changes to the 'advace' options, applying every 'dropdown', one at a time, on each page/tab. Then, I noticed the blank field for "DHCP Client ID"; I added "iMac" to the field, hit 'ok', then 'apply', and pulled a DHCP address before I could move my hand from the mouse. I am not sure if the issue is related to the way the DHCP ethernet header is crafted (DHCP request/respone) but, the Wifi config doesn't appear to require a 'DHCP Client ID' to pull an IP Address/access the network.

I am still testing the connection by pulling files from both my local network and the Internet but, it appears to have resolved the issue for me. As a note, I have not had any connectivity issues (Ethernet or wifi) with my Mac Mini, either Macbook Pros, iPhones, iPads or with guest devices on the network (one exception, a similar issue with a Nintendo Wii connecting via wifi).

This is my first post (at least I don't recall another one) but, I noticed others have included some of the following (local network) information. I am using a Cisco ASA 5505 FW, which is also providing DHCP for network devices along with a couple of switches (one managed, two unmanaged/passive). The first test I completed, I pulled a 201.4 MB video file, stored on a Drobo FS, across my local network in about 6 seconds... that is the best performance I have seen compared to other network devices.

Hopefully, this will help a few others with this issue!

T573, this worked for me.

My symptom was that my iMac Ethernet connection would work OK plugged into my Time Capsule, but not plugged into the wall (which is connected to a SonicWall firewall). The downside is that I only get 50 Mbps through the TC, whereas I get 100 Mbps directly. That's yet another sad Apple story and the issue is well-documented elsewhere.

Based on your suggestion, I read up on Client ID and it seems that the most common value for this field is the port's MAC address. I plugged this in and my network port is now working. So far so good. Thanks a lot! - I have been searching for quite some time. I will re-post if I have any issues in the future with this.

My ethernet port on my 27" iMac (mfc date mid 2011) seemed to be out today. I'm the original owner of this computer and keep my OS up to date. El Capitan has been installed and updated and it has never given me any problems. So I suspected the physical port might have given out.

I tried nearly all of the suggestions here; but nothing good happened. A call to Apple tech support revealed that several had reported a non-functioning ethernet port recently and a reinstallation of the OS fixed it. In my case, a reinstallation, following the parameters outlined below, did fix my ethernet port:

-Note: I had a wireless connection working at the time.

-First, shut down the computer completely.

-Then Press the Power button, and immediately hold down the keyboard combo: command-R. Be patient as this is slower than a reboot.

-A graphic will eventually appear, once the Mac does its hardware tests. (In my case the graphic alternated between a picture of my wireless keyboard, pointing to the on/off button; and a picture of the wireless mouse, pointing to its on/off button. The tech instructed me to turn them off and then back on again. Once that was done, I could use the mouse.)

-The graphic had a next arrow which led to OS X Utilities.

-In OS X Utilities there were four choices. I used two of them, as instructed by the Tech.

-First the tech advised to use the "Get online help" option. This brings up a browser. Type in google.com (for example) to make sure you are connected (and thus can download).

-Then, go back to the Utilities screen and this time choose "Reinstall OS X". Reinstallation takes about an hour. There will be a progress bar.

-At this point the Apple Tech set me up for a callback the next morning to follow up and find out if this solved the ethernet port problem.

It did work. After the installation, the computer rebooted automatically. I logged in and reviewed the System Preferences > Network panel; and Ethernet was connected. So it wasn't a bad port, after all. The Tech said it indicated that something in the Operating System had gotten corrupted. Not sure how that happened, but am happy that it was not a bad port.

I felt it important to come back and report both the problem and what turned out for me, after a frustrating day, to be the ultimate solution. Hope it helps someone.

Indicators of this same problem (and potentially thus, the same solution) might be as follows:

(as suggested by daniel Azuelos) In the Terminal app window, type: netstat -I en0

-Before the reinstalled OS: the command, netstat -I en0 result showed table column labels, but no associated data:

Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll

--After the fix: it showed a few rows of columnar data, below these same column headers.

-Before the reinstalled OS: Apple menu > About this Mac > Hardware > Ethernet Cards

said: "This computer does not appear to have any PCI Ethernet cards installed."

--After the fix, it showed:

Broadcom 57765-B0:

Name: ethernet

Type: Ethernet Controller

Bus: PCI

(etc. etc....)

BSD name: en0

Kext name: AppleBCM5701Ethernet.kext

(etc. etc....)

-Before the reinstalled OS: Apple menu > About this Mac > Software > Disabled Software

Two software names appeared in a list that I had not seen before. One was related to BCM5701Ethernet.kext.

--After the fix: the list was blank, and the following note appeared: "No information found."

Fran,

This JUST happened to me! Thank you for your detailed post. I'm going to try your solution.

Currently Netstat -I en0 gives me a bunch of zeros, and my System Report indicates no ethernet adapter installed (other than my USB-Ethernet dongle that I'm using for access right now)

Thank you for your post - I'll report back.

just reinstalled OS X while preserving settings and data. the problem solved for me 😉

I followed Fran's advice and the problem was solved for me as well.

Wonder if it was an update which screwed us up - and if this will be a common problem in the next 24 hours.

Anyway - ethernet port works again. Thank you Fran for your well documented solution!

The ethernet on my iMac stopped working this morning. After ruling out ISP and modem issues (I connected an old MacBook and older iMac via ethernet without any problem) I called Apple. Apparently it's a known issue and they are working to fix it. I'd have to download the system software via wifi on Australia's rather prehistoric copper cable internet system so will wait to see if there is an update before I reinstall OS X. But I suspect there won't be a quick fix otherwise.

The Ethernet port on MY 27" iMac was not working when I started it this afternoon. Symptoms identical to described by others -- WiFi still works, netstat shows zero data. Internet system reinstall -- ugh. With my bandwidth that will take a full day.

das Problem scheint gelöst ….

W-Lan deaktivieren und dann die Datei "Macintosh HD/Library/Preferences/SystemConfiguration/NetworkInterfaces.plist" in den Papierkorb.

http://www.maclife.de/news/sicherheitsupdate-imacs-macbook-pro-deaktiviert-ether net-10075457.html