Setting a booking window



I've tried setting restrictions and creating a custom rate plan, but for the life of me, I can't figure out how to close my booking window to the next 6 months only....   I am syncing with airbnb which has that setting, yet my booking.com calendar shows that anything beyond a year is open for booking....   see the image.


For now, I've set my daily rates to an exorbitant amount to try to prevent those bookings from happening...


Does someone know how to do this???   I'm stumped.