When we hear comments on the news about Britain lagging behind the world in productivity, I think you must be the sample demographic.
Here’s the reason for outage for all the geeks The downtime was due to an upgrade from Centos 7.3 to Centos 7.4 and an incompatibility with OVH servers using the NVMe SSD drives in Raid. When the update occured Grub was unable to locate the boot partition and thus could not load the operating system. It appears that this is a rare issue that only affects certain hardware configurations. Due to your server having some of the most bleeding edge hardware out there you were caught up in the bug. There should be no issue going forward now that the appropriate link has been made with Grub.
That reminds me of a conversation I had last week at work with the most defensive bloke in the world. Me "That machine is broken" (I'm paraphrasing here) Him "It was OK yesterday" Me