Proxy configuration in .NET Web.config. See https://gist.github.com/jhorsman/bb2863ae2779c46982b79dc016d7ff49 for .NET Core
<system.net>
<defaultProxy>
<proxy
usesystemdefault="true"
proxyaddress="http://localhost:8500"
bypassonlocal="False"
/>
</defaultProxy>
</system.net>