Colocar em web.config:
<system.net>
<!– ASP.NET Proxy Usage for HttpWebRequests
“usesystemdefault”
false – stops the server using the default proxy configuration or proxy
auto-detection.
“bypassonlocal”
true – this tells all requests to a local address to ignore configured proxies.
–>
<defaultProxy>
<proxy usesystemdefault=”false” bypassonlocal=”true”/>
</defaultProxy>
</system.net>