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Fix Nginx 502 Bad Gateway: Upstream Connection Refused - Group Policy Method to Enable Windows Defender Real-Time Protection-How to Fix Cloudflare 521 Error on Apache Servers

Updated 2026-07-28 09:09:16office-tools
Fix Nginx 502 Bad Gateway: Upstream Connection Refused - Group Policy Method to Enable Windows Defender Real-Time Protection-How to Fix Cloudflare 521 Error on Apache Servers
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.

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