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Fix Nginx Upstream Connection Refused Behind Cloudflare - How to Fix Cloudflare 521 Error with Firewall Settings-VSCode Dart IntelliSense Not Working: Step-by-Step Fix

Updated 2026-07-28 07:51:10cloud-software

Fix Nginx Upstream Connection Refused Behind Cloudflare - How to Fix Cloudflare 521 Error with Firewall Settings-VSCode Dart IntelliSense Not Working: Step-by-Step Fix

Prepare

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Validate

Document

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Record the exact option, command, or setting that changed the result.
Keep a rollback note if the workflow affects shared files or team settings.

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