I have an iPhone 5 and iPad air 2. Recently I've tried to sync music via Spotify but I can't see my device on my Mac. I am sure that they are all connected to the same wifi I shared by my Mac. Even if I connect my iPhone via USB, I still can't see my device pop out on my Mac. I've tried to relaunch and even reinstall the app on my phone and Mac, but it still fails to show the devices. How can I solve this problem?