While trying to add and index a new webpage in Google Webmaster tools, you may receive the following message in Crawl -> Fetch as Google -> Fetch & Render console – Temporarily unreachable.
The message means Google can’t access or crawl the page. What most likely happened is Google Bot returned a 404 error most likely because the crawl URL was incorrect. However, if your website is experiencing downtime, the link may not be accessible at all. Double check the URL you are trying to index by copying/pasting it into a new browser window and see if it renders.