NotifyMDM allows the use of the Apple Push Notification Service (APNs) Certificate to unlock additional functionality and control of iOS devices.  While there are certainly many benefits to using the built-in MDM protocol of iOS devices, there are a couple of items to note:

The proper delivery of an APNs is contingent upon the functionality of the Apple Push Notification Service.  In the event of a glitch in the delivery process, NotfyMDM has a built-in based off of the Device Connection Schedule.   Therefore, if there is a problem with the Apple server, changes made from the NotifyMDM server may not be implemented on iOS devices immediately.

The device may return a "NOT NOW" to the NotifyMDM server, even when the APN is properly sent to the device.  This status occurs when a device is locked, sleeping or not in a state able to complete a requested command.  When the device returns a "NOT NOW" status, NotifyMDM must rely on the device to check in with the NotifyMDM server when it is again in a state where it can receive updates.  Note: The exception to this is when a device receives a high security command, like a Full Wipe.  It cannot respond with a "NOT NOW" status when it receives this command.