You probably have an issue with web socket origin whitelist, or you are trying to access Qlik Sense using a device with a self-signed certificate that doesn't like self-signed certificates and it's disconnecting the web socket.
Make sure your websocket white list is filled out in virtual proxy configuration and see if that resolves your issue.
See here for more information.
thanks for the quick answer
i add in the whitelist and see the same error, see the attached
what do you recommend?
Thanks a lot
Capture.PNG 17.0 K