Faulty Ethernet port on 27" iMac - how to be sure?

[ascender]

I've been noticing some problems with my 27" iMac recently where the Ethernet port has no IP address when waking from sleep and powering on. Seems to fix itself shortly after, but I put it down to some sleep issue.

Today though, I installed a new network switch and could not get the iMac to connect over Ethernet. Tested the cable OK, switch ports with other machines etc. After a few hours, the Ethernet port came up.

I was just wondering, before I phone Apple, is there any way for me to run diagnostics on the network port? I'm not going to lug this thing to the Apple Store only for them to not find anything wrong with it, but I feel like I've eliminated everything else from the equation now.

Any ideas?

Thanks,

Mike.

[ascender]

Definitely something funny going on here.... If Ethernet fails, will it start to use Airport? A few times I've come back and Airport is on but I've always had Ethernet as the primary connection.

[avihappy]

Definitely something funny going on here.... If Ethernet fails, will it start to use Airport? A few times I've come back and Airport is on but I've always had Ethernet as the primary connection.

Try backing up and reinstalling OS X? This sounds like a software issue. Maybe you could try loading windows in boot camp (or just put in a Ubuntu liveCD (http://www.ubuntu.com/) if you don't want to install any other OS) and see if it works fine (if it does work in an alternate OS, then it rules out any hardware issues)?

[Lordedmond]

I've been noticing some problems with my 27" iMac recently where the Ethernet port has no IP address when waking from sleep and powering on. Seems to fix itself shortly after, but I put it down to some sleep issue.

Today though, I installed a new network switch and could not get the iMac to connect over Ethernet. Tested the cable OK, switch ports with other machines etc. After a few hours, the Ethernet port came up.

I was just wondering, before I phone Apple, is there any way for me to run diagnostics on the network port? I'm not going to lug this thing to the Apple Store only for them to not find anything wrong with it, but I feel like I've eliminated everything else from the equation now.

Any ideas?


Thanks,

Mike.

when you put in the router did you power everything OFF not sleep and then restart?

I presume you know that the Ethernet and the router negotiate a lease that lasts for a pre determined time its about 1 hour and after that it is renegotiated . while the lease is not correct you will have no network

from off or sleep the lease needs to be confirmed . my 24 inch 2009 iMac needs about 20 secs from sleep to get the network started