Internet connection lost after sleep - Ethernet

OK, 24 hours later, after switching the energy saver setting for the computer to "never sleep", have put the MB to sleep numerous times, shut it down, restarted, everything I could think of that resulted in not being able to connect to the internet after sleep. So far, this workaround is working! Not a permanent solution but may work for some. thanks allygill!

Misery loves company. I am so sorry so many of my fellow macheads are having problems with their ethernet connectivity, but so glad to find out I'm not alone! My year and a half old 24" iMac began losing ethernet connection after awakening from sleep a few weeks ago. Network settings state "Ethernet cable is unplugged or the device at the other end is not responding." At first, I could wait two to five minutes and the connection would suddenly occur. I thought it might be my Motorola Surfboard cable modem, but after two 240 mile trips (I live in the country; first Motorola Surfboard Extreme modem couldn't be seen by cable provider), it was doing the same thing with the newest modem. The problem has continued to get worse, so that now I have to re-establish connectivity by unplugging and replugging the ethernet cable. Sometimes once; sometime multiple times. The problem occurs independently of whether or not the computer is plugged directly into the modem or the Airport Express router and whether or not anything else is plugged into any of the other ports on the back of the computer. Renewing DHCP lease does not correct the problem. An older MacPro connects just fine via ethernet and my iPhone and iPad connect without problem via WiFi. I've tried three different ethernet cables with same results. I do not have "Wake for network access" configured. Seems to me it's a problem with the mac. Looking at this forum, it indicates a logic board replacement is required. Has anyone else had to do that?

Message was edited by: Couchcowboy

Oops! I meant to post to a different forum. I was looking at several forums (fori?) at the same time and clicked on the wrong one. Sorry!

I'm experiencing exactly the same problem.
I bought the mac about 2 weeks ago, and have the Sleep setting set.
When I come back the next night, there is an error that the Internet connection has been lost. I can still access the wireless connection using an iPhone and iPad without a problem.
I need to reboot the machine.
If I return to the Machine after a 1/2 hour, it takes ages to reload the sites.
I have a Belkin N wireless router and a Motorola Surfboard Cable modem, but I don't think this is where the issue lies. I've followed the previous posts but most are too old and I thought there may be a new resolution.
Or do I need the network card replaced?
Many thanks in advance

Apple just released OS X 10.6.5

http://support.apple.com/kb/HT4250

One of the fixes in the list is "Improves reliability of Ethernet connections."

We'll see if this fixes anything, I've since turned off sleep to avoid loosing my ethernet connection. I will try sleeping my iMac with this update.

I have a 24" iMac, 10.6.5, ethernet wire, having the same problem after waking from sleep. On router to Airport to cable modem. Restart fixes every time. No problem with devices using the wireless (iMac, MacBook Pro, iPhones, iPad).

That's really strange. I've been using my iMac since 2006 without any problem, everything started after the last update (10.6.5).

When I wake up my iMac Firefox and Thunderbird always work fine, Twitterific says that I'm offline so I open Safari and discover that it's offline too. Pings from terminal work without issues.

The offline status disappears if you disconnect/reconnect the LAN cable (and I see a "network configuration changed" in system.log) or do another sleep/wake up cycle.

My iMac continues to lose Ethernet connection after sleeping. It will reconnect at times by putting it back to sleep and then re-awakening. Unfortunately, this same maneuver sometimes causes the iMac to suddenly sound like a jet engine taking off, with a very loud fan noise that won't quit until I put it back to sleep and then let it set for twenty minutes or so and then wake it back up. If I immediately reawaken after the fan problem, it immediately returns. The other way I can regain connection is by unplugging my ethernet cable from the back of the computer and re-plugging it back. It will sometimes take anywhere from 1 to 6 "replugs" to get the Ethernet to reconnect.
My iMac is only a year and a half old and has all the most recent updates. As I've stated elsewhere, I have unplugged all peripherals, disabled all startup software, done all maintenance scripts, etc., all with no improvement. Someone in another forum said they had to have their mother board replaced to correct the problem. Any ideas?

My iMac i7 27" has just started doing the same fir about a week. It is really frustrating me now.

I just thought I would add my voice to the discussion. I've had my 27" i3 for a couple of months now and for the last two days, when I wake it up from sleep in the morning, the internet connection is lost on chrome and safari, but NOT firefox. Strange.

I'll add mine too,

24" iMac, never noticed any problems until the last patch around a week ago. Since then, ethernet is dead almost everytime after waking.


Coupled with my HDMI issues on the ATV2 I'm starting to lose the faith.... 😟

my 27" started doing this too....


Whats odd is the whole IP layer doesnt disappear, i can still ping websites and connect to IP services on my network but its like safari just doesnt know whats going on.

I think its due to my mac not going to sleep properly. It has been playing up recently as well. If i put the imac to sleep (option-fn eject) and wake it up the internet starts working again.


strange

My MBP started doing this a few weeks ago when I installed 10.6.5. When I wake from sleep the ethernet connection shows as "cable unplugged" even though it is plugged in. Unplugging and plugging again has no effect. I fire up AirPort, connect to the router wirelessly and I get on the net. After about 20-30 minutes the ethernet connection starts working. I have an old Belkin ethernet switch and thought that might be the problem but even if I bypass that and connect the cable directly to my MBP from my router, the scenario described above still occurs. A mystery...

I've slogged through this thread and tried a number of the possible fixes to no avail. It's obvious there are Mac users here with different problems- some can't connect at all after sleep without reboot or unplugging ethernet cable, some find re-establishing the connection takes a minute or two... I am in the latter category.

My brand spanking new 27" iMac i7 is directly cabled to my AEBS, but it will take anywhere from 30 seconds to two minutes for my internet connection to be re-established after waking from sleep. It's extremely annoying in that usually the reason I am waking up my iMac is to use the internet.

FWIW I was using a Mac Pro running 10.6.5 and the exact same cable, AEBS and setup before and had no such problems. That points likley to a hardware issue. I can also hook my MacBook Pro up to the AEBS using the same cable and have no issues upon waking from sleep. We have several more Macs and Apple products in the house on WiFi and no Network issues with them at all.

I guess it's a tech support call for me and probably a new network card. If I find that solves the problem I'll be sure and post about it here.

Message was edited by: art4mad

Same problem here, some programs are dead after system sleep. If i only set disks and display to sleep no problem.

I experience the problem mainly with Apple programs. If i try Safari, Mail, "System Update" all reports no connection to the network, Firefox works flawlessly at the same time.

It must be a OS related problem. It seems to me like there is some core component of the OS that not get a signal that the computer no longer is at sleep.

After a failed wake-up i tried the following (seen in another post):

sudo ifconfig en0 down
sudo ifconfig en0 mtu 1500 up

Temporarily solved the problem to after next sleep.