Network slower through Mini Dock

[Charles Krug]

We've upgraded cabled network speed in our office from 100mb/s to 1000mb/s.
It appears that when a network cable is run directly into a T530, it connects at 1000.
But when the same cable is run to the port replicator (4338-35U), it connects at 100.
The specs on the MiniDock Plus series 3 include "Gigabit Ethernet".
The PC & dock were purchased in December.
Will get a USB ethernet adapter for troubleshooting, or maybe as a permanent solution.
Anybody had a similar experience? Thanks,
Jim

[basketb]

Have you tried a different cable?
Do you have another Thinkpad you can put into the mini-dock?