Thanks for assisting us with DDOS testing (not willingly I know).
We have suspended the stress testing on this server after you have enabled Cloudflare I'm Under Attack mode and the site remained in down state afterwards for most the of world, for more than 4 hrs up till the ceasing of atk.
We are currently in development of systems to directly penetrate defences of a number of JS-based CDN protection providers (inc. Cloudflare, Incapsula etc.), without the knowledge or access of the origin IPs.
Great work on the server maintenance and configuration btw, handling 15K concurrent users is generally more than sufficient.
Happy New Year!