I would start scanning a local network to see if there's any devices that I can't identify. If there are, I would try to trace them down, and, if unsuccessful,

I would start scanning a local network to see if there's any devices that I can't identify. If there are, I would try to trace them down, and, if unsuccessful, turn the router off and switch to mobile hotspot. This is under the assumption that the cameras don't store the data locally, which they probably do. In that case, I don't have any ideas what to do if you can spot them on the local network but can't trace them down physically.