Solved: DoS Attack
This afternoon, our servers were targeted by a large-scale DoS attack. This also affected our own website, which is why it was unavailable for a short period of time.
It took some time before we located and blocked the culprits. The attacks are still going on at this moment, this may cause sites to be a bit slower. We are in the process of installing additional firewall's to repel the attack.
We are also going to report to the relevant authorities.
Apologies for the inconvenience and thank you for your understanding.