IssueError message occurs while trying to connect to any Tableau Server page:
The connection was reset
The connection to the server was reset while the page was loading.
The site could be temporarily unavailable or too busy. Try again in a few moments.
If you are unable to load any pages, check your computer's network connection.
If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web.
Connecting attempt is visible (and successful with code "200" or "302) in the Tableau Server access*.log file in "C:\ProgramData\Tableau\Tableau Server\data\tabsvc\logs\httpd" folder. For example "GET / HTTP/1.1" request for home page.