Hi All,
Apologies for my absence. I am not much better than when I went on leave from work back in February, but here I am. For the first time in months, I will be working on something FOG related 
I am tasked with imaging a bunch of Lenovo T495S laptops. We see the following behavior on the T495S laptops and our X1 Carbons that are already deployed. Neither of these devices have an integrated Ethernet NIC (i hate this).
To remedy the whole “missing a vital component of a modern enterprise computer” thing we use a pair of Lenovo docks. We currently have a Gen 1 Lenovo USB-C dock and a separate Gen 2 Lenovo USB-C dock.
The problem is that we are presented with two options: Use the docks’ MAC addresses to image the laptops, thus having to join the domain and name each manually, or somehow make MAC pass through (an option to enable in the BIOS) work.
It seems that though the docks have their own MAC’s, there is also an internal MAC for a Lenovo accessory that turns a special usb-c port on the side into an Ethernet port. With using the dock, we are always stuck using each of the two Dock MACs for imaging. We cannot do full registration because it only recognizes the two docks, not anything with the devices themselves. Auto-Naming/registering/joining is not an option using the docks because of 2 MACs vs like 50 Laptops.
Regarding MAC pass through, the devices PXE boot and load into the fog menu perfectly with the correct internal MAC. However if you go anywhere past that (deploy image or Full Registration) it hangs up and times out. I see when it tries to use the Dock MAC to start any task past the FOG menu.
So, it seems the pass through breaks somewhere in the PXE environment and it reverts to the Dock MAC.
So our options are currently order a couple of the special Lenovo Accessory ports and cross our fingers that the dock mac elimination fixes this (back ordered until Mid-July though) or to try to see if getting pass through working is feasible. I am working from home 95% of the time, but please let me know any info you need for the next time I go in. We are still 1.5.6 and are willing to upgrade to 1.5.8 if need be. As always, CentOS 7 is the OS and client is…whatever shipped with 1.5.6 (I’m so out of touch I forget what version…)
Thanks folks!