Reason unknown but it was not possible to view any page in the forum except the index page and the registration pages (??) It was also possible to log in using the log in option at the bottom of the index page and use your user control panel. Judging form that the problem has lasted at least a couple of hours.
All the rest of our web services do work as they should
I have no means of fixing this - but I have alerted those who have the means
From Sunday (around 10 am UTC) it works again.
Look at Clem’s comment.