[ltp] 100mbit only when docked?

Richard Neill linux-thinkpad@linux-thinkpad.org
Mon, 30 Mar 2015 00:38:46 +0100

> On visual inspection the port looks just fine.

It's not always easy to see this kind of damage to the springs.

>> Try repeatedly running ethtool, while wiggling the end of the cable,
>> or inspect the socket very carefully.
> It spits out the cannot advertize message almost immediately after I hit return on my keyboard, which makes me feel like maybe there's something else going on preventing gigabit?

You can check the hardware and cables of most ethernet devices by using 
TDR (time-domain reflectrometry). This sends pulses up the cable, and by 
timing it back, you can find which core is broken, and how
far away the break is. Annoyingly, I've never seen a Linux driver for 
this, but many thinkpad BIOSes support it as an advanced option within 
the network settings.