The hosts file you're maintaining... is that on the same Windows system where you installed the Portal instance? Why did you use 192.168.1.2... that's a commonly used default IP for home routers, etc. but wouldn't call back to the local server.
127.0.0.1 is your localhost/loopback address. If you goal was to launch a browser on the server where the Portal instance is installed and to be able to call the application using the 'sapadmin.com' host name, you needed that to point back at 127.0.0.1.
Additionally, you shouldn't be using https as the protocol in that URL. Using the wrong protocol can/will direct your traffic to a different port on the target server (compared to http). If you don't have any applications listening on that port (443 for example), then you'll get no response except a 404 error.
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