Servers can get overwhelmed by DDoS attacks and similar malicious traffic, and they may even crash.
If you are not protected, your hosting providers has to take steps to protect infrastructure and other customers from your malicious traffic. They normally end up sending your hosting and packets to /dev/null never to be seen again, and that puts your services offline. This is often known as nullrouting or blackholing.
You have just been DDoS victimized by some random force on the internet, now your provider added insult to injury with an instant and often long lasting null. This is the daily experience at hosting companies without DDoS Protection.