Welcome to the Apple Support Communities.
Simple questions first:
Have you tried another Ethernet cable?
Have you tried connecting (the same cable) to another port on your Ethernet switch or router?
Have you tried another computer with a wired Ethernet port using the same cable and the same port? (in case your Ethernet port is defective or damaged).
Since your Mac less than a year old, a true hardware defect would still be covered under Applecare.
When I start up my computer I would have this problem where if I don't have my ethernet cable plugged in when it first starts up it won't be recognized.
That's normal with many, if not most, Mac models. It is not a hardware or software problem; it is in the design.
The way it works is that if there is no live (powered on and ready) device detected by the Mac as being connected via ethernet during startup, the ethernet bus will be turned off.
I don't know why it is designed that way.
The result is that ethernet is not 'hot pluggable', at least not directly. If you have an intermediate ethernet hub, switch, or router in the connection scheme, then you can connect a device to the hub/switch/router after the Mac has been booted and have it be recognized. This is, of course, dependent upon the hub/switch/router having been on and warmed up and connected to the Mac before booting the Mac.
WiFi uses a different port/bus, so is not subject to this restriction. Ditto for firewire and USB, both of which are 'hot pluggable' by design.
Though the thing I'm wondering about is how long it takes for the computer to recognize the ethernet cable after it's been plugged in. With USB, when I plug it in it starts up, but at times when I plug in the ethernet cable nothing happens until I restart the computer.
Thanks for the suggestions, if I have some spare time I might drop by the genius bar. I will post updates if I encounter any.
Not sure what you're trying to accomplish.
Resetting PRAM is easy to do yourself:
Even if you aren't comfortable adding/editing/deleting the network locations, it's fine to LOOK at them.
Deleting Network preference locations:
(I'm on OS X 10.6 'Snow Leopard', so your screens might look a bit different)
Start at , System Preferences, Internet & Wireless, Network
Click on the 'Location' up/down button at the top to reveal a pop-up list...
(full names obscured for security - yes I have MANY custom locations defined)
The 'active' location profile is the one with the check-mark at the left.
and select Edit Locations at the bottom of the list.
Click the - (minus) sign to delete Locations, and the 'Done' button when you are finished, to confirm the changes/edits/deletions.
The + (plus) sign adds new Locations, and the 'Gear' lets you duplicate or rename an existing Location.
OK thanks.. I'm having the same issue that I've seen here and on threads all over the place.. Using my Macbook, the Ethernet connection is useless, even though it says it's connected..
The same ethernet cable works in every other pc in the house, only the macbook has the issue.
Seems that, from above:
"I went to the Apple store today since I had time and the genius simply deleted the preferences for the locations I had accumulated in the network panel and reset PRAM. Works fine now, thanks for all the help. I was glad it didn't have to do with the actual ethernet adapter."
resovled it.. so I was just wondering how we can do that without going to see a "genius"..
So you've determined that it's not likely caused by an Ethernet cable problem, since the same cable works on other computers.
If you have not already visited these pages, here are Apple support guides to network troubleshooting:
What does Network Preference diagnostics show?
, System Preferences, Internet and Wireless, Network, select Ethernet from the left column, and click the Assist Me button at the bottom. Then select the Diagnostics button.
After you've reset the PRAM and edited Ethernet network Location preferences without resolving the issue, or if this seems beyond your level of comfort or expertise, then it's time to visit a Genius.
Message was edited by: kostby
I just got off the phone with apple and they wanted me to do the same and delete all of my preferences for networking, I was reluctant as I have many stores static address for different office locations. But given the idea of delete, I simply delete the one device from the troublesome configuration and added it back. It worked and much safer than going to delete a bunch.
So again, my "ethernet" was saying connected as well, but from command line "ifconfig -a" was not showing connected. I deleted "ethernet" and then added it back in through the network preferences. All good now.
I'm running 10.7.3. on a 15" macboo pro 2.8GHz Core i7
My client has this exact issue on two MacBook Pros. I've tried everything listed in this thread (and links) and more--and the problem persists. I'll spare you my exhaustive troubleshooting steps but here's my workaround. If I plug the MacBook into a small unmanaged switch--it works. All other methods of connecting the Ethernet port do not work. I've plugged directly into several of our managed 48-port gigabit switches, removed/readded the port, PRAM, SHIFT-CTRL-OPTION-PWR, delete Network Prefs, check for "automatic" settings, manual IP config, and on and on. I did not try reinstalling the OS, taking it in or calling Apple (even though my client has support). My end user seems to be happy with the local switch workaround--but I'm not.
okay, totally stumped. Can't get my LAN port working on my iMac. Reset Pram, made sure connections are set to automatic. Funny thing is it won't even light a port on my switch. My switch is handing out a lan IP address using DHCP. Funny thing is if I take my imac down the hall and connect to another drop in my office going through a router handing me a 192 address, it connects no problem. I can connect my windows based lap top in no problem as well as my macbook into my office drop. Just not the iMac. Wireless works fine. Need help.
I too am having som sort of network issues. My late 2011 15" MacBook Pro has been working flawlessly since purchase. Since the upgrade to OS X Maverics, I've had an odd networking issue. My Mac is joined to a Windows Domain Network where the DC is a Windows 2012 Standard Server, again its never been an issue. Now I am having local network issues and getting the following issues in the Network Diagnostics page:
I cannot access network shares or other resources either. BTW, my user account is a network admin. so permissions are not the issue.