I have wide experience working with corporate proxies. Configuration is usually working well with
But if you have configured the proxy and it’s impossible to work with git (always getting 443 error) try to check if you have a remote.origin.proxy bypassing your configuration.
git config --list --show-origin
If you check that “remote.origin.proxy” is configured as empty value try to unset it or almost set it with your corporate proxy:
git config --add remote.origin.proxy "http://[yourproxy]:[yourport]"
And since several enterprise sites have untrusted certificates I recomend you to avoid certificate checking if you are using ssl:
git config http.sslverify false
git config --global http.sslverify false