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Fix Firefox Secure Connection Failed Due to Antivirus Interference - Fix Windows Defender Real-Time Protection Not Working with Network Error-PowerShell 504 Gateway Timeout: Diagnosis and Resolution Checklist

2026-06-13 18:17:09browser-issues
Fix Firefox Secure Connection Failed Due to Antivirus Interference - Fix Windows Defender Real-Time Protection Not Working with Network Error-PowerShell 504 Gateway Timeout: Diagnosis and Resolution Checklist

Final checklist

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