Did you WHOIS the IP? probably a forge anyway.
I would try to ban the IP in your server admin panel anyways.
Just to check....
Type your IP:port in the browser to access the DNAS
Look at the squared box on this and click it.
Where it prompts you here, type "admin" as the name, and type the password you use to stream for the DSP as the password.
from their you will see a function to ban IP's