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Fix Cloudflare Origin Certificate Not Trusted by Browser - How to Resolve Cloudflare 521 After Server Update-Router DNS Configuration for NXDOMAIN Error

Updated 2026-07-28 06:42:53office-tools
Fix Cloudflare Origin Certificate Not Trusted by Browser - How to Resolve Cloudflare 521 After Server Update-Router DNS Configuration for NXDOMAIN Error
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.