Hi Rich,
I suspect you already have the NIC driver for the device that Lenovo lists on their site, but if not here is what I am seeing.
I have seen a couple instances where the seemingly correct driver was added to the boot.wim , but they did not actually end up working. At least once I have seen a driver listed as 'Windows Blue' that ended up working for someone when all other drivers were not working. Here's a quick way on how to test drivers to see if you can get one working within WinPE as a point of reference.