Last night (20th April) the webites were down for some reason or other for several hours.
(http://gallery.orpington-astronomy.org.uk/albums/userpics/10004/daily-oas-20-21-Apr-2023.png)
It looked from here as if the database server wasn't working (the blue track on the graph above) from about 9:30pm BST last night (the time axis is UTC). Simple file fetches (the red track on the graph above) seem to have been working, but as the sites all need databases, the lack of a database server means the site's down...
Something got rebooted a bit after 7am BST, and the sites were then accessible again. If I find out any more I'll add a note here.