If you are on a corporate network, ensure ports 443 and 5223 are open, as these are required for Apple MDM communication. 3. Active "Stolen Device Protection" (iOS)
Temporarily disable Stolen Device Protection in Settings > Face ID & Passcode before attempting to enroll the device again. 💻 Fixes for macOS Users Check Your Serial Number
On newer versions of iOS, can block the installation of certain security profiles.