Garmin Connect Calendar Sync

Hi,
Is it possible to sync may Trainingworkouts to the watch via Wifi?
If I click at the arrow button (next to year on the calendar page) it shows me connect your device to the network. Then I click at sync on my 5x but it still shows searching on the webpage. (the 5x shows synchronizing) after 30sec it has finished syncing, but there is still no new workout (only the one I synced by the connect android app)

do I need to sync them via cable if I want to sync them all. syncing only one by one with the phone is anoying. does anybody have an idea how many workouts I can safe on the 5x?

thx for your time and answer!

M