TCP port 443 is used as a fallback if port 5223 is blocked.
For iCloud Mail, ensure "Push" is enabled under Settings > Apps > Mail > Accounts > Fetch New Data . Network & Connection Requirements How to Fix "Apple Push" Errors
Resolving "Apple Push" errors requires a tiered approach, as the issue can stem from end-user device settings, network restrictions, or backend developer configurations. TCP port 443 is used as a fallback if port 5223 is blocked
Provider servers sending notifications must allow outbound traffic on ports 443 or 2197 . Developer-Level Fixes start with these common device-level solutions:
If you are an individual user not receiving notifications, start with these common device-level solutions: