Identity Engines 9.0.3.0 uses SMBv1 as the transport protocol which by default will be disabled on Windows Server 2016 deployments. Additionally Ignition 9.0.3.0 uses either the service account OR anonymous NTLM bindings (depending on configuration) - both of which are also disabled by default with Windows Server 2016.
Upgrade to Ignition 9.3.3 for the best 'baseline' support for Windows Server 2008 / 2012 / 2016.