zhizhu
Home / office-tools / How to Fix Cloudflare Error 521: Web Server Down - Enable Windows Defender Module via PowerShell-Troubleshooting Windows Update 404

How to Fix Cloudflare Error 521: Web Server Down - Enable Windows Defender Module via PowerShell-Troubleshooting Windows Update 404

2026-06-13 17:47:55office-tools
How to Fix Cloudflare Error 521: Web Server Down - Enable Windows Defender Module via PowerShell-Troubleshooting Windows Update 404

Final checklist

  • Confirm that the same symptom is gone after a restart or refresh.
  • Keep the smallest working change and undo temporary diagnostic settings.