Abstract: Methods for data synchronization in a computer network of a restaurant management system, corresponding devices and a corresponding system. A client receives a selected dish, stores it in a client order list and sends a corresponding synchronization message to a controller, wherein the message comprises a synchronization time and entries of the client order list. The controller receives the message, updates a controller order list accordingly and generates a current synchronization time. The controller receives a second synchronization time from a second client and selects entries from the controller order list, depending on the second synchronization time and on the current synchronization time, and sends a second synchronization message, which contains the selected items, to the second client.