We can drill down on the bandwidth history/usage reports to get stats by individual IP address. The problem with this is that IP addresses are often temporary. It would be useful if the router also reported the MAC address alongside the IP address.
Sometimes hovering the mouse over the IP address in these detailed reports shows the MAC address and the friendly name for the device. This is not documented.
Also, if the friendly name is known (or can be looked up) it would be useful to include this too as a field that is always displayed.