Hôtel-Restaurant Dahm - Luxembourg

Yesterday, I and my Luxembourgish friends joined an Army March in Diekirch. We saw a restaurant on our way and planned to have some beer because we thought that the restaurant was a nice one. After 15-20 minutes waiting in the terrace, no one came to serve us, so one of us went inside. Nobody was there. He took a wifi password board to show us, google the phone number of the restaurant, and called them whether we can order something. A server finally came and took our order. 5 minutes after, a woman came to us and took the wifi password board, screaming at us in Luxembourgish (my friends explained it after it happened) that "the board is hers, we don't have manners, etc" and kicked us out from the restaurant. As a foreigner who just moved here, I was so shocked! It's so intolerable for someone who knows hospitality to treat someone like this! Even in my home country, nobody acted this way even if the customers made mistakes. I am so disappointed and I will make sure that my friends and family won't visit this place.