Thinkpads Forum

With my T400, it always seems to connect at 100Mbps even though I've got it plugged into a gigabit switch on my desk. I can set it to 1000Mbps, but I like to keep my computers on auto-negotiation so that it works if I have to temporarily plug into a 100Mbps device ie. configuring an AP, and with auto-negotiation it keeps defaulting to 100Mbps.

Anyone else have this problem?

Have you tried a different network cable, and/or different network to plug into?

if connected directly - consider your onboard ethernet chip went semi-bad if cabling, switches or routers are Gigabit

If connected through dock - dock's ethernet is bad, I had same problem.

Is it a managed switch? Port configuration the switch could be funky, but you have probably already looked at that.