The hosting service we use seems to have fallen over this afternoon. The OAS sites have been unavailable for quite a few hours (from about 18:00 BST to 22:30 BST). The hosting provider's support system also went down, so I assume whatever caused the trouble was affecting the entire hosting system. Hopefully it's now back and working...
(http://gallery.orpington-astronomy.org.uk/albums/userpics/10004/daily-oas-20170906.png)