"The connection either timed out or was lost. Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host."
There are two possible causes.
1. If you are getting this error randomly while opening the report.
It is likely that your Analyzer site's authentication setting is not setup correctly, most likely both Windows and Basic authentication both are enabled. You should only have one or the other enabled - ASP.NET + Basic or ASP.NET + Windows, never both Windows and Basic together.
2. If you are getting this error while using Chrome browser only:
This most likely has to do with an AppSettings key called "AnalyzerInternalUrl", please make sure the URL is a valid URL that can be used on the web server. In other words you should be able to run a browser on the web server then use this URL to connect to Analyzer.
<add key="AnalyzerInternalUrl" value="http://localhost/Analyzer/" />
If the URL is not valid then change it to a valid URL.