Yarn Classic vs Modern: Proxy Settings and Config Files
Use the configuration format for the Yarn release actually running instead of mixing Classic proxy keys with modern YAML settings.
Check the Yarn release inside the failing project first:
yarn --versionA project-selected release can differ from another checkout or terminal. Use its matching configuration format.
Yarn Classic uses the older .yarnrc form:
proxy "http://203.0.113.10:8080"
https-proxy "http://203.0.113.10:8080"Modern Yarn uses camelCase keys in .yarnrc.yml:
httpProxy: "http://203.0.113.10:8080"
httpsProxy: "http://203.0.113.10:8080"Replace the documentation endpoint with an HTTP proxy from your service or the HTTP proxy list. These are different formats, not interchangeable names in one universal file. A Classic hyphenated key pasted into modern YAML can fail at configuration before the proxy is tested.
Identify the file the selected release reads, including project and surrounding/home lookup rules. A more-specific hostname setting can also choose another route. The registry remains the package-metadata source; replacing it with a proxy IP does not configure forwarding.
After correcting the file/key, observe an operation that actually needs network access. A cached result can hide an invalid route. Use the actual failing hostname and error to decide whether the next issue is routing, authentication or certificate trust.