iPhone push notifications does not work

Hi everyone,

I’m experiencing a very strange and persistent issue with push notifications on my iPhone and I’m trying to understand whether this is an iOS bug or a hardware-related problem.

Device: iPhone 14 Pro Max

iOS: 26.3 (updated today, but on iOS 26.2 was the same)

• After a reset, push notifications work normally for a short time
• After several minutes or hours, all push notifications stop completely
• This affects all apps (WhatsApp, Instagram, Messenger, etc.)
• System messages may sometimes still come through
• Apple Watch also stops receiving notifications (mirroring the iPhone)

What I’ve already tested:

• Reset All Settings
• Sign out / sign in to iCloud
• Reset Network Settings
• Reinstall apps
• Disable all Focus modes, Screen Time, Low Power Mode
• Tested on both Wi-Fi and LTE/5G → same behavior
• Works briefly after reset, then stops again

What can I do more?