All schools are protected by network firewalls and the majority of networks will not have the Apple Push Notification service enabled to allow access. This can stop features from most MDM solutions which require several ports to open to talk to the Apple Push Notification service. In order to allow access you will need to open the following ports.
Port TCP 443 (https)
Port TCP 1640 (SCEP)
Port TCP 5223 (APNS)
Port TCP 2195 (APNS)
Port TCP 2196 (APNS)
This has been the case for several popular MDM solutions such as profile manager and Meraki. If these ports are not open you will not be able to push settings or receive notifications from your iOS devices.
If you are behind a grid internet provider for example SWGFL (South West Grid for Learning) You would need to contact the grid for a change request on the ports above.