In order for this to work, you must
1 have a computer which was synced to a iDevice at least once in the past
1a the computer must not have had iTunes cleared in any of several ways, the simplest being to merely delete it and its preference files
1b the iDevice must not have had its sync settings cleared in any of several ways, the simplest being to go to the Settings and clear it
2 both the computer and the iDevice must be on the same wireless net
2a the iDevice must have been set to sync wirelessly
2b in order to sync wirelessly the iDevice must usually be plugged into power
2c iTunes must actually bloody work, something which in my experience rarely happens when you bloody want the damn thing to bloody work; I've lost count of the times when iTunes bleats 'the device "important iDevice" cannot be synced because it cannot be found' unless and until I plug the damn iDevice in by USB
2d the wireless net had better have the correct BSID, the computer had better have the correct network ID, the router had better behave itself
3 the user had best kneel and say five Hail Steves and a Damnation to Bill. Three Damnations if the computer in use runs Windows. Four if Windows 10. Seriously, if you forced a prisoner of war to use iTunes under Win 10 you'd be up before the War Crimes Tribunal. Hardened Taliban fighters in Gitmo scream like little girls when they see the dreaded iTunes logo booting up.
4 the sync had better run properly; I've lost count of the number of times that I start to sync an iDevice, iTunes says its syncing, the device says its syncing... two hours later its still syncing. There's a problem. Restart the iDevice. iTunes reports an error, can't find the device 'important iDevice', a check shows that last sync was last night. Try again. This time the sync takes a few minutes. All is well.
5 the version of iOS and of iTunes had best be compatible. If the version of iOS is too old, iTunes can't find the iDevice. If the version of iTunes is too old, the iDevice refuses to connect.