It may due to APNS expiration or incorrect
- Please go to Apple > APNS > APNS Info
- Check if the current certificate is expired. If yes, please follow the instructions to update
- If no, please go to Device > Device Management
- Tap on the Device Name which is disconnected
- In Device Detail page, scroll down to APNS Cert UID
- If there is a notification of APNS is incorrect, please copy the last part of the UID (should be a mix of characters and numerics)
- Go to https://identity.apple.com/pushcert to find the certificate matching the last part of the device UID. Download that certificate and update to ESP again