Just means that the firewall is doing it's job and blocking mass requests for connections from that discovery service. If whoever is running that is not behind a proxy server, or a NAT, they could have easily sent out a request to do a scan on the network they are on, which could mean your internet connection.
If you are using a software firewall, you may want to get a router and use that instead, as it is, your IP is visible to the internet and is open for things such as this.