Can't synch iPhone 4s using WiFi; iTunes drops WiFi connection
I am trying to set up things so I can sync my iPhone 4S (IOS 8.3) over WiFi to my PC (Windows 7, most recent iTunes). What I am seeing is that iTunes will connect to the iPhone, get the name of the phone etc, and perform an initial sync. But if I wait a moment and then try to do anything iTunes displays a message saying that it is looking for the phone, and then the phone's info in iTunes disappears. Then I have to restart either the iPhone or iTunes. If I go to the wireless router, and log in, the iPhone is still connected and Youtube still works (through the WiFi) so the WiFi is still working. So as far as I can tell all the hardware is still working it is just something in iTunes dropping the connection. I have also tried to start a Sync from the phone (after waiting a bit after the initial connection) and a similar thing happens. This is making it impossible to do much in the way of management of the iPhone through WiFi since every time I try to do anything the connection is not there anymore.
The iPhone's OS has been restored a number of times and the network settings have been reset to factory defaults, and this has not changed anything.
Anyone have any idea what to do next?
GOES_M
iPhone 4S, iOS 8.3, Windows 7, Most recent iTunes