Hello,
I used the same settings like you
and I can communicate between ctrlX CORE OPC UA client (version 1.20.0) and the OPC UA server of the IoT-Gateway (version 3.7.3).
After I trusted the certificate of the OPC UA client inside the IoT-Gateway server.
I guess, I also could reproduce your error
by using a different IP address "192.168.1.22", instead of the IP address "192.168.1.21" of the IoT-Gateway.
Could you please check, if the ctrlX CORE can reach the IoT-Gateway on your selected IP address 192.168.3.58? Could you describe your network topology?
The wrong port could lead to the same error, but I see inside you screenshots, that the port "9999" is set inside the IoT-Gateway and the UA-Expert.
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