Required Settings were done already
As I mentioned "We were able to open hub using http, but suddenly on one day we were unable to open the hub using http"
After restart of services we were able to open using http again without any issues .
Researching to know what could be the issue ?
Appreciate any help .
You might have enabled both HTTP and HTTPS, but issue might be because some other webserver like (IIS/Apache etc) may be running in background and blocking your 80 port. After server restart it would have allocated again to Qlik sense. you can check Task Manager(resource monitor) which will show the Applications using the port 80(http) / 443(https).