On Premise Enrolling AndroidPlus devices on a network with no internet connection
Yes - the MobiControl server has (almost) full internet access.
Are the devices already running Oreo? If so you may have to use Android Enterprise.
It is Oreo devices. I'm downloading the the Enterprise agent along with the mcsetup.ini on the device and enroll as a device owner. Then the Enterprise plugin is installed. This usually works - but not here. I suspekt it has something to do with certificates. A Soti Engineer is looking at it later today.