Hi Nikola.

The GoogleBot performs these tests simulating a very slow connection. For this reason, many times some images will not be loaded, or will count as "Temporarily unreachable" only for this reason.

This does not mean that all of this material is not indexed in your website. This can normally happen for data heavy pages which take a while to load, and also if the server is a little slow in delivering the content, but as previously mentioned, it will in no way affect the Rating of your website. Also feel free to perform additional similar tests with other services if you're unsure of the result, but keep in mind that this specific error indicates no real problem if Server's response speed.

Thank you

Stefano