set http_proxy=http://username:password@proxy:port
set https_proxy=
http://username:password@proxy:port

Don’t use quotes around the parameter

Encode passwords with

php -r "echo urlencode('Pa$$w0rd!');"

winsh winhttp import proxy source=ie

Self signed certificate in certificate chain

npm config set strict-ssl false

c:\programdata\gemrc :ssl_verify_mode: 0