Kitchen order screens for a restaurant group

Design the system that sends orders from point-of-sale terminals, the website and delivery apps to the kitchen display screens in each of 120 restaurants. Each restaurant has 2 to 6 screens (grill, fryer, expediter), and an order must appear on the right screens within 2 seconds, in the order it was placed, with later changes such as a removed item or a cancellation applied after it. Restaurants have unreliable internet: orders from the restaurant's own POS terminals must keep reaching the kitchen when it drops, and a screen that reconnects must show exactly the open orders. A busy restaurant handles about 300 orders an hour at peak. Describe the message flow, ordering, and how screens recover after a disconnect.