The dongle has three ports but only 2 is used:

1. Power: marked with a lightning bolt.
2. RS232: THIS is the port ÖoB uses!
3. ETH: This is NOT used by ÖoB.

RS232 and ETH is identical port types; RJ45. So it is a common mistake that the cable is connected to ETH instead of RS232.
If it is incorrectly in ETH, the terminal will say "waiting for ECR" connection after boot.

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This is how the cables should be connected to the ports.
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By dragging the cables through the loop at the bottom in this picture the cords will be more safely secured so they don't slide out of the

ports as easily.
Especially the power cord as it does not have a locking mechanism like the RJ45 contact has.