The Star Micronics receipt printer uses Bluetooth to connect, so if you are experiencing difficulties, please try the following steps
Unpair the printer: go to the iPad's Bluetooth settings, click the (i) next to the connected printer and select "Forget Device." Make sure to do this for any iPads connected to the printer.
Then turn off the iPad's Bluetooth.
Next, reset the printer
Find the small red "RST" button on the back. You will need something small like a pencil tip to press and hold down for 3 seconds. It will print out a small note about auto-connection.
Switch the power button off and then on again.
You can now pair the printer with the iPad you want to use it with (it only works with 1 at a time).
For more control over your printer, search for "Star Micronics" in the App Store and download the Star Setting app
Star Setting lets you manage settings like whether the printer pairs automatically after being turned off or disconnecting from the iPad.
You can also rename your printer (for example POS1, POS2, etc.).