This is most commonly caused by a loose ethernet/network connection, please confirm:
- That the printer is turned on and when you press the feed button, paper comes out (if not, please switch the printed on and off from the mains)
- That the ethernet lights where the ethernet cable at the back of the printer are lit up
- That your printer and POS are on the same network e.g. if you are running a hotspot for your customers and a separate one for your business, make sure your printer and POS are on the same network!