WLS to External WS Connection through Proxy Server

WLS Experts,

We are trying to connect to external webservice endpoints on the internet through a proxy server. We have setup the following proxy connection details in the setDomainEnv.sh and managed server's startup arguments. However, we see for one endpoint sandbox.paypal.com the connection is happening through proxy and getting successful response, but for another endpoint bpoint.premier.com.au it isn't hitting the proxy server, as we don't see requests on the proxy and getting connection failure.

We have verified that its domain names don't coincide with the ones setup in http.nonProxyHosts .  Infact both the end points are responding fine when testing with Wget from the same server.