Ethernet printer requires network cable connection to the router, commonly used for the kitchen.
Alternatively you can use Wi-Fi printer with the same model.
Bluetooth printer is suitable for environment like kiosk/pop up store.
Simple to setup, but not able to support more than 1 printer per device generally.
Star TSP-100 is the only USB printer that is supported by MobiPOS.
A special USB cable has to be connected to the iPad's lightning port in order to work.