I suspect the issue in two ways.
1. Access Accesspoint to the IIS server itself .
Try accessing the servername.domain.com and check if you are able to get a IIS default page.
Try servername.domain.com/qlikview and check if you can see the accesspoint with the specified user.
2. If both of them are working, then the issue is with the Opendoc URL.
try to connect to the dashboard from Client's accesspoint and copy the URL again.
Localhost - should be replaced by your servername.domain.com
Document= make sure document path is correct
host= this holds your QVServer name. check the same in QMC.
We are not checking anything on authentication and authorization as the same user works on server.