Need advice for home network monitoring

Hi all, I have about 20 devices (Desktops, laptops, tablets, smartphones, PVR, etc.) that connects on my router (Asus RT-AC66U - http://ca.asus.com/en/Networks/Wireless_Routers/RTAC66U/).

I just received and configured that router. It can gives me real-time bandwidth monitoring, but for the total only. I see there's traffic, but I can't see which MAC or IP is currently using that bandwidth.

Anyone has a suggestion on which way I could have a real-time monitoring of my home network that will tell me current usage of the bandwidth of all connected devices (wired and wireless) with the assigned IP address?

Thanks a lot!