When a remote host has an IP address that starts with any of 0, 10, 127, 172 or 192.168, it gets rejected due to it being considered "local". This rejection occurs on the importing server, not the remote host, but Wordpress Importer still reports the error as "Remote server did not respond", which is in this case incorrect and misleading.
The error message in WordPress Importer's source code
The WordPress function that rejects the request due to its IP address