Jetpack doesn’t seem to do anything

I have about 5 sites on one server, spanning three different virtualhosts. They all get slammed with fraudulent login attempts, and the attempts themselves eat up my server’s resources.

I installed Jetpack on every site. I also installed a plugin called Simple History where I can see when people try to log in.

After activating brute force protection, I can look on any site and see the same person trying to log in, 7, 14, 21 times, from the same IP address, and they never get blocked. So it seems to me like brute force protection isn’t working at all. Is there a way I an troubleshoot this?