EPSON DM-D30 : Customer DISPLAY.
Access to your SumUp App > Settings ⚙️.
Go to Printers > you will see all the connected printers.
Disconnect the printer you will plug the Customer display on. To do that you need to slightly move the line of the printer with your finger to the left.
As you are sliding the line to the left, click on the option Disconnect that will appear in red.
Turn OFF the printer.
Connect the Customer Display’s USB cable to your printer.
Turn ON the printer.