Remote login of user does not work

[fmauser]

I have a Ubuntu 18.04 client with Veyon 4.3.1 installed on and veyon master 4.3.1 installed on a Windows 7 machine. After booting up the client machine, with logon screen displayed, any attempt to remote login a user on the client machine seems to fail. Whereas after succesful login of a user on the client machine veyon master establishes the connection with the client and all the remote functionalities appear to work properly. Is this behaviour a limitation due to my particular system or a consequence of a misconfiguration?