Another point. . . Unless you are using a dual-band router, if there is at least one non-N device actively connected to your wireless network, all "N" devices will throttle down to the speed of the slowest wireless device.
For example, if you have a wireless "G" device connected to your network, while your laptop and cameras are "N", all devices will connect at "G". The easiest way to check this is to access your router web interface and see what band the router is currently using (should say "N").