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Fix Windows Defender Blocked by Third-Party Antivirus - Cloudflare Wildcard SSL Not Working? Try These Fixes-How to Fix Cloudflare Error 521: Web Server Is Down

Updated 2026-07-28 11:14:55browser-issues
Fix Windows Defender Blocked by Third-Party Antivirus - Cloudflare Wildcard SSL Not Working? Try These Fixes-How to Fix Cloudflare Error 521: Web Server Is Down
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.