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Troubleshooting Pairing

Troubleshooting Pairing

Owned by Karel Kyovsky
Last updated: Apr 30, 2025 by Charles Wernicke

Pairing explained here: Establishing Trust between Terminal and Server - Terminal Pairing

  • Review that article before attempting troubleshooting.

This article contains a list of recommended steps to pair a terminal.
The recommended steps differ based on the terminal's current state and the version installed on it.

This guide assumes your server version is at least 20230801.

Jump here to the right section that applies to your case:

Terminal firmware version 20230801 (or newer)

Pairing steps

Deployment Scenario

Terminal state

Actions to take

Notes

Deployment Scenario

Terminal state

Actions to take

Notes

Terminal operates in Deployment Scenario A

Terminal was paired in past to this server and has VPN configuration already generated.

  1. Set on terminal server’s host/ip via advanced administration. Terminal should show error screen with pairing code displayed.

  2. On server in CAS new pairing request will appear on terminal list page.

  3. Approve the pairing request.

  4. Terminal will pair and connect to master service via VPN channel.

If terminal displays “VPN connection error” it means that you probably didn’t generate VPN configuration.

 

Terminal operates in Deployment Scenario A

Terminal has never been paired to this server and doesn’t have VPN configuration generated yet.

 

This case applies for example to new terminals that has been purchased.

  1. Create terminal on server.

  2. Generate VPN configuration for terminal.

  3. Set on terminal server’s host/ip via advanced administration. Terminal should show error screen with pairing code displayed.

  4. On server in CAS new pairing request will appear on terminal list page.

  5. Approve the pairing request.

  6. Terminal will pair and connect to master service via VPN channel.

If terminal displays “VPN connection error” it means that you probably didn’t generate VPN configuration.

 

Terminal operates in Deployment Scenario B

Terminal has never been paired to this server.

 

This case applies for example to new terminals that has been purchased.

  1. Create terminal on server.

  2. Set on terminal server’s host/ip via advanced administration. Terminal should show error screen with pairing code displayed.

  3. On server in CAS new pairing request will appear on terminal list page.

  4. Approve the pairing request.

  5. Terminal will pair and connect to master service.

 

Terminal operates in Deployment Scenario B

Terminal was paired in past to this server.

 

  1. Set on terminal server’s host/ip via advanced administration. Terminal should show error screen with pairing code displayed.

  2. On server in CAS new pairing request will appear on terminal list page.

  3. Approve the pairing request.

  4. Terminal will pair and connect to master service.

 

Unpairing steps

Unpairing should only be done when necessary.

Currently, there are two reasons for unpairing:

  • when the terminal is stolen, or

  • when the server is reinstalled or migrated.

Deployment Scenario

Terminal state

Actions to take

Deployment Scenario

Terminal state

Actions to take

Terminal operates in Deployment Scenario A

Terminal is paired and connected to VPN and master service

  1. Unpair terminal via action menu in list of terminals.

  2. Terminal will unpair and show error screen with pairing code displayed.

Terminal operates in Deployment Scenario B

Terminal is paired and connected to master service

  1. Unpair terminal via action menu in list of terminals.

  2. Terminal will unpair and show error screen with pairing code displayed.

Terminal firmware between 20190130 and 20230801

Follow these steps if the firmware is a newer version than 20190130 but older than 20230801.

Pairing steps

The machine will need to undergo terminal upgrade to version 20230801 before it can be paired. The good news is that gate service should take care of it automatically.

Deployment Scenario

Terminal state

Actions to take

Notes

Deployment Scenario

Terminal state

Actions to take

Notes

Terminal operates in Deployment Scenario A

Terminal was paired in past to this server and has VPN configuration already generated.

  1. Set on terminal server’s host/ip via advanced administration.

  2. Terminal contacts server and displays following Error: Terminal unpaired

  3. After a while gate service automatically upgrades terminal to a newer version. This step will be performed automatically.

  4. Terminal should after a while start showing error screen with pairing code displayed.

  5. On server in CAS new pairing request will appear on terminal list page.

  6. Approve the pairing request.

  7. Terminal will pair and connect to master service via VPN channel.

If terminal displays “VPN connection error” it means that you probably didn’t generate VPN configuration.

 

Terminal operates in Deployment Scenario A

Terminal has never been paired to this server and doesn’t have VPN configuration generated yet.

 

This case applies for example to new terminals that has been purchased.

  1. Create terminal on server.

  2. Generate VPN configuration for terminal.

  3. Set on terminal server’s host/ip via advanced administration.

  4. Terminal contacts server and displays following Error: Terminal unpaired

  5. After a while gate service automatically upgrades terminal to a newer version. This step will be performed automatically.

  6. Terminal should after a while start showing error screen with pairing code displayed.

  7. On server in CAS new pairing request will appear on terminal list page.

  8. Approve the pairing request.

  9. Terminal will pair and connect to master service via VPN channel.

If terminal displays “VPN connection error” it means that you probably didn’t generate VPN configuration.

 

Terminal operates in Deployment Scenario B

Terminal has never been paired to this server.

 

This case applies for example to new terminals that has been purchased.

  1. Create terminal on server.

  2. Set on terminal server’s host/ip via advanced administration.

  3. Terminal contacts server and displays following Error: Terminal unpaired

  4. After a while gate service automatically upgrades terminal to a newer version. This step will be performed automatically.

  5. Terminal should after a while start showing error screen with pairing code displayed.

  6. On server in CAS new pairing request will appear on terminal list page.

  7. Approve the pairing request.

  8. Terminal will pair and connect to master service.

 

Terminal operates in Deployment Scenario B

Terminal was paired in past to this server.

 

  1. Set on terminal server’s host/ip via advanced administration.

  2. Terminal contacts server and displays following Error: Terminal unpaired

  3. After a while gate service automatically upgrades terminal to a newer version. This step will be performed automatically.

  4. Terminal should after a while start showing error screen with pairing code displayed.

  5. On server in CAS new pairing request will appear on terminal list page.

  6. Approve the pairing request.

  7. Terminal will pair and connect to master service.

 

Terminal firmware 20190130 and older

Pairing steps

Terminals with this version are ancient.
The machine needs to undergo two consecutive terminal upgrades. The good news is that the gate service should take care of it automatically.

Deployment Scenario

Terminal state

Actions to take

Notes

Deployment Scenario

Terminal state

Actions to take

Notes

Terminal operates in Deployment Scenario A

Terminal was paired in past to this server and has VPN configuration already generated.

  1. Set on terminal server’s host/ip via advanced administration.

  2. Terminal contacts server and displays following Error: Terminal unpaired

  3. After a while gate service automatically upgrades terminal to a newer version. This step will be performed twice automatically.

  4. Terminal should after a while start showing error screen with pairing code displayed.

  5. On server in CAS new pairing request will appear on terminal list page.

  6. Approve the pairing request.

  7. Terminal will pair and connect to master service via VPN channel.

If terminal displays “VPN connection error” it means that you probably didn’t generate VPN configuration.

 

Terminal operates in Deployment Scenario A

Terminal has never been paired to this server and doesn’t have VPN configuration generated yet.

 

This case applies for example to new terminals that has been purchased.

  1. Create terminal on server.

  2. Generate VPN configuration for terminal.

  3. Set on terminal server’s host/ip via advanced administration.

  4. Terminal contacts server and displays following Error: Terminal unpaired

  5. After a while gate service automatically upgrades terminal to a newer version. This step will be performed twice automatically.

  6. Terminal should after a while start showing error screen with pairing code displayed.

  7. On server in CAS new pairing request will appear on terminal list page.

  8. Approve the pairing request.

  9. Terminal will pair and connect to master service via VPN channel.

If terminal displays “VPN connection error” it means that you probably didn’t generate VPN configuration.

 

Terminal operates in Deployment Scenario B

Terminal has never been paired to this server.

 

This case applies for example to new terminals that has been purchased.

  1. Create terminal on server.

  2. Set on terminal server’s host/ip via advanced administration.

  3. Terminal contacts server and displays following Error: Terminal unpaired

  4. After a while gate service automatically upgrades terminal to a newer version. This step will be performed twice automatically.

  5. Terminal should after a while start showing error screen with pairing code displayed.

  6. On server in CAS new pairing request will appear on terminal list page.

  7. Approve the pairing request.

  8. Terminal will pair and connect to master service.

 

Terminal operates in Deployment Scenario B

Terminal was paired in past to this server.

 

  1. Set on terminal server’s host/ip via advanced administration.

  2. Terminal contacts server and displays following Error: Terminal unpaired

  3. After a while gate service automatically upgrades terminal to a newer version. This step will be performed twice automatically.

  4. Terminal should after a while start showing error screen with pairing code displayed.

  5. On server in CAS new pairing request will appear on terminal list page.

  6. Approve the pairing request.

  7. Terminal will pair and connect to master service.

 

 

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