ipad remote management

I am managing 60 ipads for use in an educational setting and have them enrolled in a MDM system using Configurator 2. It is very common for IOS upgrades to fail in one way or another requiring individual re-preparation and updating. With the update to IOS12.01 a new problem has presented itself where some units fail to be configured with an error message indicating that the host server could not be found. The problem units have a wifi connection and only a handful have failed to progress when all the other have succeeded. I can skip the configuration step but need to complete this before they can be used. Why is this happening and how can I fix it?