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2012 iMac dropping Ethernet connection

A

at1987

macrumors newbie
Original poster
May 11, 2012
9
0
I have a user who's on a brand new Lion iMac and is having constant network issues. I know there have been a lot of issues with the Wi-Fi in Lion, and this seems to have the same symptoms with Ethernet. I've eliminated any physical problems with cables/jacks. Sometimes renewing the DHCP lease will fix it, and sometimes it needs to be rebooted a couple times before it works. Almost every morning she said she has to reboot as many as 3 times to get it to connect, then at random points throughout the day it drops the connection.

Any ideas?

Edit: It turns out it's a 2011 model.
 
Last edited:
blueroom said:
What type of router are you using?
Click to expand...

I believe it's a Cisco 1841 but I'm not absolutely sure because we currently outsource our networking stuff (soon to be brought in-house).

Smartie said:
Do you have enough IP addresses available in the office? Is this user last in line to the router?
Click to expand...

Yes. I believe we have about 100 free addresses in the DHCP pool. I even tried putting her on a static IP but still had the same issues. I'm not sure what you mean by "last in line" to the router...the building is all wired into a patch panel which goes into our switches. Again, I'm not positive of the network layout, but it appears that all the switches are trunked together, so everybody is on the same logical level.

It looks like I'll be spending a chunk of Monday on the phone with Apple.
 
Try using "static" IP addressing inside your iMac.
Also remove IPV6 or IPV4 (if using IPV6).
Adjust MTU size - for your unique LAN.
Use static DNS settings.
Use static speed and duplex settings as well.

These changes stopped my wired connection from dropping.
 
MacOG728893 said:
I've been waiting for the 2012 model for sometime. You're so lucky you got it first :rolleyes:
Click to expand...

Yeah...I'm assuming it's a '12 since it arrived about 2 weeks ago.

Edit: I was wrong...2011 model.

Spike88 said:
Try using "static" IP addressing inside your iMac.
Also remove IPV6 or IPV4 (if using IPV6).
Adjust MTU size - for your unique LAN.
Use static DNS settings.
Use static speed and duplex settings as well.
Click to expand...

I've tried static configs for IPv4 and DNS.

It didn't occur to me to check on the MTU, speed and duplex. Automatic works fine on the rest of our hosts. I will look into that on Monday though.

Thanks for the help.
 
Last edited:
If the speed and duplex are set to auto negotiate on the switch, you will want to keep your side set to auto. If you hard set your side and the other side tries to negotiate, the switch will fall back to 10 half.

If you can hard set both sides, you will be golden.
 
Lance-AR said:
If the speed and duplex are set to auto negotiate on the switch, you will want to keep your side set to auto. If you hard set your side and the other side tries to negotiate, the switch will fall back to 10 half.

If you can hard set both sides, you will be golden.
Click to expand...

Unfortunately we don't have access to our switches because they're managed by a contract firm who tends to be quite uncooperative. So I have no idea what the switches are set at.
 
Auto sensing can cause the problems you describe so that would be my first port of call. The very least the firm managing the switches should be able to tell you is the settings for speed and duplex.
 
Thanks for the replies, I'm going to see if I can make any headway by changing the MTU and speed/duplex settings today.
 
at1987 said:
Yes. I believe we have about 100 free addresses in the DHCP pool. I even tried putting her on a static IP but still had the same issues. I'm not sure what you mean by "last in line" to the router...
Click to expand...

Only relevant if you have limited number of IP addresses. I meant if she is the last person booting up each day. Didn't want to ask if she is always late to the office ;)

In addition, as others have written, I would also try to with closing down IPv6 and use static DNS settings.
 
Smartie said:
Only relevant if you have limited number of IP addresses. I meant if she is the last person booting up each day. Didn't want to ask if she is always late to the office ;)

In addition, as others have written, I would also try to with closing down IPv6 and use static DNS settings.
Click to expand...

Aahh okay haha.

I haven't tried anything yet today, as it seems to not be acting up. Could this possibly be a NIC hardware issue? I would think that a mismatched config would fail more consistently.
 
I just read the title and thought your joking right? No Ethernet port? Like what's the point. I now realise you were talking about last years model. Might I suggest you edit the thread title.
 
Apple fanboy said:
I just read the title and thought your joking right? No Ethernet port? Like what's the point. I now realise you were talking about last years model. Might I suggest you edit the thread title.
Click to expand...

I would edit it if I could. Notice I edited the post though...

So...no issues this week. She's been turning it on, giving it about 5 minutes and then the connection works perfectly all day. So I'm calling this a Lion issue since networking seems to be one of the weak points in general. We may still call Apple one of these days, but for now we're just going to see how it goes.
 
at1987 said:
I would edit it if I could. Notice I edited the post though...

So...no issues this week. She's been turning it on, giving it about 5 minutes and then the connection works perfectly all day. So I'm calling this a Lion issue since networking seems to be one of the weak points in general. We may still call Apple one of these days, but for now we're just going to see how it goes.
Click to expand...

Some may argue with you. But in my IT experience, it is MOST DEFINITELY a Lion issue. What gives, Apple???:confused::(
 
Well, the problem is back. It was okay for a couple weeks, we were just booting it up in the morning and letting it sit for 5-10 minutes and that seemed to work. Recently it's started throwing fits again though.

As much I'd absolutely love to drag the thing through the parking lot, I suppose apple care might be the more practical solution.

It seems that Apple has become too focused on retina displays and superfluous features, and are falling short of OS X's functional reputation.
 
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