Hi!
According to the W3 standard document, HTTP response code means:
The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method.
Have you tried to run the client and server without HTTPS, that is, using plain HTTP?
If you are having problems setting up either plain SSL or SSL with mutual authentication in connection to web services, please have a look at my book that contains complete examples on how to do both:
http://www.slideshare.net/krizsan/scdjws-5-study-notes-3085287
Best wishes!