Digital ocean went unresponsive on the Friday which was immediately picked up by our up-time monitoring system. When trying to reboot the Callwell web server it wasn't possible because of a message saying "Events for this Droplet are currently disabled while the hypervisor is under maintenance". This stopped any actions from being available on the droplet and there was no planned maintenance. This was eventually described by Digital Ocean support as a fault (below). The solution to this was to quickly implement our emergency back up plan to rebuild a new server based on the most recent web server back up (Sunday) which went successfully and was back up within 30 minutes.