It says it cannot reach my URL. What now?

Three usual causes. The site is behind a bot protection layer that refuses anything without a browser fingerprint, in which case the reading genuinely cannot be taken and neither can several of the systems this tool is modelling. The page is slower than the nine second timeout. Or the document is larger than the 1.5 MB ceiling.

The second and third are worth knowing about in their own right. A page that a nine second timeout cannot reach has a problem that is not about this tool.