Due to circumstances at least partially beyond our control, Sumo Forum experienced an uncharacteristically long outage. The root cause of the issue was a database server update that turned out to be incompatible with the PHP version running our forum software. The issue was discovered by forum administration during the early hours (local time) of Tuesday the 10th. It was diagnosed and reported along with the probable cause and a suggested fix to our ISP by noon.
The ISP, however, refused to investigate the issue because it was not reported by "a registered contact person of the customer". It wasn't until late Wednesday that I was able to reach @Kaikitsune Makoto to confirm the service request was indeed coming from a legitimate source. Our diagnosis of the core issue seems to have been correct and the fix has now been implemented, correcting the issue.
Our regular service has resumed, the management wishes to apologize for any inconvenience caused.
TL;DR: Forum was down between Tuesday and Thursday, apologies.