how do i block a user doing illegal download on my network

Good day there. do any of you know how to block an App to download a torrent?
i have someone doing a lot of torrent downloads on my network and ask to stop and keeps doing it.

I have a shaw cable router and an Apple "white tower" router and would love to know how to block the port of the app so called Transmission so it completely stop doing torrent download.

Thank you

via Canadian Mac Forums at ehMac https://ift.tt/N418cin