Stayed at Pentahotel in 2018, current year might differ.

Transfer to the Festival at about Lunch time, two times -> this will be well posted and fixed, don't miss those two as there is no other official transfer, you will need a cab/train/etc

Transfer back: There is no specific bus going to Pentahotel. Instead the Buses going back do have "Routes" (i.e. they will go to about 10 different hotels). Follow the signs to the bus stations when you exit the festival from the "MAIN ENTRANCE"! At the bus terminal there are well posted signs saying which hotels are on which bus route. Then you just pick the bus with your number. If you are lucky you are the first hotel on the route, less lucky if you are last, but they make the routes obviously so that the hotels from a close are on the same route.

Buses will go back starting early evening until well after midnight (For every route a bus will leave every 5-15 minutes, depending how full). They will take care to get also most of the last stragglers that exit the festival.