If I'm understanding what you said correctly, your cameras are streaming when
blue iris is not running? If you close blue iris (console if not running as a service, or terminate in task manager if running as service) then your cameras should not be streaming any data across the switch. It is normal for network traffic to increase by the data stream size of your cameras when you run blue iris, as it requests the video streams from the cameras and that data will move across your network through your switch, but not your router unless you are remote viewing are remote viewing with the bi app or ui3 interface and the data will be much less than what moves on the local network. Your description of what's happening makes me think your cameras are streaming video to somewhere aside from blue iris, and then you see additional local network traffic when you start blue iris and it requests video streams. If you have not set up for streaming aside from blue iris you need to check your camera config in the camera admins. And possibly ban the cameras from internet access in the router if they are in fact streaming direct somewhere outside your network.