Lol, this wasn't my choice really! The JACK server's default UDP listen port is 3000 with the netone backend, so that is default port that ETH-68 sends to. This can be adjusted on both ends
See, for example, Cloudflare's stories of issues caused by misconfigured systems appropriating the "1.1.1.1" address for their own purposes: https://blog.cloudflare.com/fixing-reachability-to-1-1-1-1-g...