This solution works, but the problem continues to recur after a day or so. This is a work around in my opinion because despite buying new iOS devices, cycling power and toggling states, despite just installing a new i7 Mac Mini, and having a multi-point Airport Extreme/Airport Express network that otherwise works well, WiFi sync reliability still eludes me. In all other ways, my iOS device work well and that is particularly in that they sync data very well via iCloud. iCloud sync is mind blowing reliable, but merely syncing wirelessly to iTunes on my desktop Mac Mini...not so much.
There is another thread on the Apple Support Communities that refers to WiFi sync problems since iOS 6, that has been open since September, 2012 and is quite active with almost 450 replies and no reliable solutions. Both threads appear to address a common problem with WiFi sync to iTunes on Mac (mostly, since there are PC iTunes users as well) computers. This is predominately an iOS device to Mac iTunes sync problem.