var connMgr = ComponentMetaData.RuntimeConnectionCollection.GetRuntimeConnectionByName(Variables.pvDataConnectionName1260).ConnectionManager;
var hcc = (HttpClientConnection100)connMgr.AcquireConnection(null);
hcc.Timeout = 300;

if (Variables.pvDataConnectionAuthorisationMode1260 == "Server")
{
    hcc.UseServerCredentials = true;
    hcc.ServerUserName = Variables.pvDataConnectionUsername1260;
    hcc.ServerPassword = Variables.pvDataConnectionPassword1260;
}
_downloadBuffer = hcc.DownloadData(); //this is the line that fails

connMgr.ReleaseConnection(hcc);
The URL being requested is along the lines of
https://reports.abc.com/def/data_extracts/filename_20170815.csv