I have the same problem.
I solved it with a bleutooth and (for my own use) spotify connect player (DENON 350 UI) in combination with a bleutooh repeater. (works well over a 100 m free view) the player costs a 350,- € although so its an expensive solution comparred with the Xair 18
The player is connected with the line in 17/18 input.
This way it is possible to work without cables and have background music available.
Who knows maybe in the future the streaming function will become available in a firmware update.
Lets hope so.