I have a Yongnuo Speedlite YN560-11. This was bought on line as a Christmas present- unfortunately the basic manual is limited and written in basic English!
I have been using in manual mode successfully with the speedlite away from the camera and not mounted on the hot shoe. In this case the pop up flash also fires which I would have liked not to have done. But reading your 1st response it appears this is necessary to send a signal to the Speedlite.
The Speedlite is fine in S1 and S2 mode - but still with the pop up operating.