The "https://getcomposer.org/versions" file could not be downloaded: failed to open stream: The connection attempt failed because the connecting party did not reply properly after a period of time or the connected host was unresponsive.

The "https://getcomposer.org/versions" file could not be downloaded: SSL: The remote host forcibly closed an existing connection.
failed to open stream: HTTP request failed!

Second question

'composer' is not recognized as an internal or external command, operable program or batch file.