Rear Plug for IBM ThinkPad

We have a bunch of IBM thinkpads of vaious model types. We have found that the rear plug won’t work for our network and that we have to use an ethernet card and dongle. With these, the network will run fine. I have tried the connection wizard and traversed (in vain) the IBM website for solutions to this. We have found this problem in the docking stations as well.

Note: We also have a few Dell laptops, and they work fine from the rear network port. Makes me wonder what’s going on with our ThinkPads.