W10 has messed up

a number of things that used to work. (3.42 x64)
I clicked the server clear log button,
I was warned to Stop the server. Check.
clicked clear log. Check.
Clicked Start Server. file permissions Warning (sorry, did not capture).
I had to shut Calibre down and let the server auto-start.
I can no longer use Localhost (or 127.0.0.1) to check operation: now I get a '404'
I must use the IP of this same machine.