@heromed Hi,
Q0 error means that the connection was refused. This error probably comes from the TCP transport layer. The server application did not accept the connection at the socket level due to some reason (wrong port or wrong address family)...
Can you try using another app (just to test) to try connect to GUI-O designer tool. For example:
https://play.google.com/store/apps/details?id=com.sollae.eztcpclient
Regards.
Kl3m3n