Our network engineer is out today so we’re not sure about the details. All we could see was that a “no internet” policy was applied to that port via our NAC, and when we disabled it, FOG suddenly worked fine. The box was booting from the FOG server via IPXE so it seems that internal network access wasn’t blocked, but again, we don’t know any specifics.

Also, I assume Steam is up to date. Steam had an known issue mid to late last year that caused orphan files in many systems. They released an update that resolved the issue and cleaned up after its self.