I have problems with wifi sync between my iPad Air and iTunes version 18.104.22.168. I use the PC version of iTunes. If I initiate the sync from the iPad, iTunes immediately starts the sync by displaying the message at the top of iTunes -- "looking for iPad". Then within a second or two, my iPad Air "disappears" from iTunes and the Devices section on the left side of iTunes disappears also. If I start the sync from iTunes, same thing happens. I DO have "sync this iPad with Wifi" checked in iTunes. The only way I can sync is to use a hard wire sync using the usb cable plugged into the iPad Air and into my computer. I have tried checking and unchecking "sync this iPad using wifi", re-booted the PC, restarted the iPad Air. Nothing works to get a successful wifi sync. I have the iPad Air with Verizon and 128 GB memory. This never happened with my iPad 3. Thanks for your ideas.