Identified the origin of the DDoS attack. Apparently, the person was just hopping through 3 IPs so looked like a targeted attack likely from a competitor. I sent the logs with incident notification to the abuse@hostprovider.com to ask them to suspend them.

Got a prompt response but took them a week to suspend this.

We were a very small team and had to stop everything to fix this-iptables and firewall etc.

We had not even launched the product and was still under development.