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Change Windows Update Port to Fix 'Already Allocated' Error - How to Resolve Cloudflare 521 Error with Nginx-Restore Default Windows Defender Configuration

Updated 2026-06-13 13:09:48cloud-software
Change Windows Update Port to Fix 'Already Allocated' Error - How to Resolve Cloudflare 521 Error with Nginx-Restore Default Windows Defender Configuration
Likely symptom
Likely cause
Safe rollback

Verification route

  • Repeat the original action, not only a simplified test case.
  • Restart the app or reload the service after configuration changes.