How to prevent most torrent downloads on a small business guest WiFi network?

I set up a WiFi network for a small local bar that a friend of mine owns. He got a letter from his ISP that someone downloaded a movie on the network- so we need to beef up restrictions a bit.

I’ve seen plenty of similar posts, and many responses seem to highlight that you can’t block 100% of torrenting . I get it, that’s fine. I just want to dissuade people from downloading movies and shit on the free WiFi. 95% is fine.

The current router doesn’t allow blocking individual ports or domains, or reducing the bandwidth on the guest network only. I’m guessing we might need to pick up a router that allows that.

Any suggestions on router models that allow the things I listed above, without breaking the bank? And after that, which ports or domains to block, or other suggestions?

Thanks in advance!