yes I am Dutch and ober is only used for restaurants. In a coffee place, bar etc. the waiting staff is called: 'bediening' from the verb bedienen (= to serve someone).
The bartender is called 'barman' and we took 'barista' in our Dutch vocabulary from Italian to address the person who makes the coffee in a coffee place.
Watch out not to confuse 'bediening' with 'bediende' where the latter means servant/butler
to clarify further:
wij wachten tot de OBER onze bestelling opneemt - we are waiting for the WAITER to take our order
kan iemand van DE BEDIENING mijn tafel schoonmaken - can someone from THE WAITING STAFF clean my table
het eten was goed, maar de BEDIENING slecht - the food was good but the SERVICE bad