WebSocket connection Issue in wkhtmltopdf while downloading invoice pdf

We also tried Wkhtmltopdf error creating PDF
and added below config, but now working.

 "restart_supervisor_on_update": true,
 "restart_systemd_on_update": true,
 "host_name": "https://mydomain.com"

Actually we are getting connection timeout error not refused or SslHandshake.

And in console, everytime getting WebSocket connection Issue.