The Dutch word for waiter is
ober

Dutch Definition

waiter
1. ober, kelner

ober	©
1. n-m. waiter
Ober, mag ik de menukaart alstublieft? - Waiter, may I have the menu please?
De obers waren druk bezig met het serveren van de gasten. - The waiters were busy serving the guests.
Dat obertje was erg behulpzaam en vriendelijk. - That young waiter was very helpful and friendly.

kelner
1. n-m. waiter (a server in a restaurant or similar)
De kelner bracht onze drankjes. - The waiter brought our drinks.
Kun je de kelner vragen om de rekening? - Can you ask the waiter for the bill?
De kelners in dat restaurant zijn altijd erg vriendelijk. - The waiters in that restaurant are always very friendly.