Since streaming portals start to implement torrents in the backend, I would like to block torrents. Best would be if this could this be implemented in the router (ac66u).
In general, the best way to accomplish this is to explicitly prioritize/allow all the "good' traffic that you're aware of and allow all other unknown "bad" traffic to go into a default configuration that blocks or massively restricts the throughput.
Since torrents are using encryption nowadays, it's hard to block them unless you know the ports where it operates. All encrypted traffic tends to look the same, so you can't tell the different between traffic from your bank or some torrent.