Hi
https://zenmine.proThere was an attack on the pool
Now everything is normal, the vulnerability was closed.
On your page it says that servers are DDOS protected. How can they go down then?

There is no real ddos protection nowadays. Botnet bandwidth is too high. Even prolexic kicked krebs out. Also layer 7 ddos appliances for bitcoin do not exist to my knowledge. And further: updates, hardware failure etc can be a cause of downtime.