Lots of timeouts using WebClient

I have been using WebClient for sometime now and experience quite a few timeouts when phone network connections are good. Like WiFi in my house. This seems to get worse on an iPhone4 as a factoid but happens on both Android, iPhone5s, and simulator. I am creating a new Task for each web call via Task.Factory.StartNew and calling WebClient synchronously from that task using UploadValues. I have subclassed WebClient to have a 20 second timeout.
I sometimes need to make synchronous calls to sequence web requests that is why I do it this way. Is there anything wrong with this approach that might be causing me problems? Is another approach better Ted