And lo and behold, while I was at work, everything dropped once again leading to an eight hour outage. We're back now, on the previously used network address block, in hopes of sticking with this new address for the usual nine month. DNS et al have been updated for the main address but I still need to update the quantian.org address.
Apologies to everybody who tried to connect in the interim, but this is unfortunately beyong my control.
Having updated the DNS entry, and thanks to quick redirection at Gandi, web traffic is already back. If you're on cached DNS data, it should get reflected "soon" too.