Try New Technology

I have seen this a few times while supporting some Mac machines (mostly wireless, so I’m not sure if this applies to wired connections) at a local business. I find that after many major updates to the OS that the users report they are unable to login when the login is a Network User. In these cases you need to login as a local user (hopefully you have an admin or roaming account with a local copy of the user profile) and let it finish all the update/questions and once to the home screen, just log out and you should be able to login as your Network User.

NOTE: I first saw this in early 2016 and again just a few days ago. It doesn’t seem to effect every machine, but just randomly.