Booting into the domain using imageassist

Greetings,

This might have more to do with the machine than with image assist but here it goes.  We have the Latitude 7400's (not 2 in 1) coming and they do not have a on-board Ethernet port, but my team will connect to Ethernet via a USB-C to Ethernet dongle.  The machine can't see the network upon boot-up to allow Image Assist do it's thing.   We have no issue if we use a thunderbolt dock, it happens only with the dongle.  The Thunderbolt to boot in the Bios is selected but I don't think that anything to with it that's mainly for PXE.   Anyone have any suggestions?