Imac with uverse slow with ethernet

I just switched to Uverse (high speed) - my ethernet connection is extremely slow, at times times timing out trying to get onto internet. Same Imac and modem work well with wireless when I unplug the ethernet cable.

My Ibook works great wired AND with the same ethernet connection.

Network settings show ethernet is connected, I tried pinging with no problem.

Spent 2 hours with AT&T, they can't figure it - say it must be the Imac - using snowleopard 10.6.3.
Any help?
Mike Shack

Dollars to doughnuts that your Network settings are the problem. What unit is doing the DHCP? and how many units in and on the LAN? Look there.

This from lifeisabeach;

http://reviews.cnet.com/8301-13727_7-20006831-263.html?part=rss&tag=feed&subj=MacFixIt

Rule out the cable - Try the ethernet cable you have connected to the iBook on the iMac.

slow ethernet

First, I tried changing the cable - no difference and worked with the laptop.

I am a network novice, and have a problem with Collin Bl's response. I went to the Network under Preferences and it has the following:
Configure IPv4 - using DHCP, no DHCP client ID in advanced -

How do I know what unit is using it and what should I change it too if I am able to find out?
Where do I find how many units "in and on the LAN" and what should it be if I find it?
Thanks
Mike Shack

Imac and modem work well with wireless when I unplug the ethernet cable

Click to expand...

must be the Imac - using snowleopard 10.6.3

Click to expand...

Mike - the reason i did not give a specific answer is i found it a little difficult to understand what exactly the problem is.
Can we assume that all works well except with the iMac that runs 10.6.3 when it is connecting wirelessly?

Yes, normal speed wirelessly if I unplug the ethernet. Also the same connection from the router works to my IBook.
Mike

Have been away for a few days - so catching up with old posts - did u get your Mac sorted?