SOAP UI error message

Dear team,

our client tries to set up SOAP UI with WSDL files.

He's installed SOAP UIversion 5.5.0 and uploaded correct WSDL files as projects. He has 2 types of the users with wich he tries to run the program.

One user is a service user with the certificate.

The second user is a personal user with password.

When the client runs the prrogram with the service user, he receives the error message:

<env:Text xml:lang="de">Web service processing error; more details in the web service error log on provider side (UTC-Zeitstempel 20210728081229; Transaktions-ID 93A8C7AFA66000C0E0060F7A4B76B5A2)</env:Text>

With the personal User ID and PW the client receives:

"remote host closed during the handshake"

It's weird because as SAP support we also tested the program on our side with the same setting and we've got no errors.

Could you please advice what should be checked and where the root of the issue can be?

thank you,

regards,

Elena