Go to Settings > Notifications and ensure "Allow Notifications" is enabled for the specific app.
Resolving "Apple Push" errors requires a tiered approach, as the issue can stem from end-user device settings, network restrictions, or backend developer configurations.
If you are developing an app and encountering errors, verify these backend and configuration steps: Troubleshooting push notifications - Apple Developer How to Fix "Apple Push" Errors
Navigate to Settings > General > Background App Refresh and set it to "Wi-Fi & Mobile Data".
TCP port 443 is used as a fallback if port 5223 is blocked. Go to Settings > Notifications and ensure "Allow
If you are an individual user not receiving notifications, start with these common device-level solutions:
TCP port 5223 must be open for devices to receive notifications. TCP port 443 is used as a fallback if port 5223 is blocked
Ensure Do Not Disturb or other Focus modes are turned off in the Control Center.