we flew iad-vie-vce a year ago. we had a passport check.
we could not find our gate. it was one of a group of 5 or so. no numbers on it, or any other gate in that area.
we had to go through a tsa form of check.
we had to tarmac check our luggage, and no luggage ticket.

we did that transfer with 30min(is legal) transfer time.