Why does the payment terminal display "communication error"?

"Communication Error" is displayed if a customer swipes their card when the payment terminal is not connected to a WiFi or mobile network. 

• If the WiFi or mobile network icons in the upper right corner are green: 
  • Restart or Power Off, then Power On, the payment terminal. 
• If the mobile network icon in the upper right corner is white: 
  • Restart or Power Off, then Power On, the payment terminal. 
• If the WiFi network icon in the upper right corner is white: 
  • Go to WiFi Settings and confirm the payment terminal is connected to the correct WiFi network and the correct WiFi password has been entered. If the network and password are correct and you still can’t connect, contact your internet service provider.