had this myself going 6S to SE 3rd Gen, interference somewhere the service still thinking my 6s was logged in, so had to completely detach it and setup SE 3rd a second time which fixed it,
This is the troubleshout i used to step by step check everything, hope it brings you the solution bro! GL
The "login succeeds then logs out" loop on a new device after an iCloud restore often points to a few things:
- Incomplete or Glitched Restore/Sync: The initial data transfer and sync with iCloud services might not have completed cleanly.
- Network Instability: The Wi-Fi connection during or after the restore might be unstable.
- iOS Glitch: A temporary software bug.
- Old Device Interference (Less Likely, but possible): If the old device is still active and trying to sync.
- Account Verification/Security: Sometimes, Apple's system needs an extra nudge to fully trust the new device.
Here’s what to try, in a rough order of ease:
Initial Quick Checks:
- Force Restart Your New iPhone:
- Press and quickly release the Volume Up button.
- Press and quickly release the Volume Down button.
- Press and hold the Side (Power) button until you see the Apple logo.
- Don't just turn it off and on; a force restart can clear more stubborn temporary issues.
- Check Apple's System Status: Make sure all iCloud services are green: Apple - Support - System Status
- Check for iOS Updates: Go to Settings > General > Software Update. Even if you just set it up, there might be a small incremental update available that could fix bugs.
- Ensure Date & Time are Correct: Go to Settings > General > Date & Time. Make sure "Set Automatically" is ON. Incorrect date/time can break iCloud authentication.