Why does Scratch appear to be associated with a different site, which our content filter has blocked?

Like many other large websites, we use a Content Delivery Network (CDN) to distribute Scratch around the world. While CDNs make Scratch faster and easier to access in many locations, it is possible that Scratch’s CDN servers can share an IP address with sites that have been blocked by your network. If your filter blocked the IP address of the other site, and the response was cached, it may also block Scratch. 

For this reason we recommend blocking sites using domain names rather than IP addresses, which are increasingly becoming shared. If your network administrator has done this and you are still experiencing problems, make sure your network filter supports Server Name Indication or “SNI”. Once you are certain that each of these are configured properly, we recommend clearing your network cache and then attempting to access Scratch again.

Please also see this article:  What domains do I need to allow to access Scratch?