Network traffic limitations on a second/extender modem-router

Hi Guys

So I've just set up a second modem router as an access point to extend the wifi coverage over the property and to give the tennant in the granny flat a stronger signal.

How I set it up is that we have the main modem/router (Netcomm NF4V) connect at the front of the house by the tv so gaming consoles and streaming can all be done over ethernet connections, I then have an ethernet cable run into a powerline adapter and have the second modem/router (ASUS DSL N55U) at the other end of the house connected to another powerline adapter. I have turned DHCP off on the second modem/router, made the SSID and password the same. I've also manually assigned an IP address to the second modem/router, to avoid conflicting with the main modem/router. Additionally I have put network traffic limits on the second modem/router under the QoS in the ASUS, to ensure the usage in the granny flat doesn't interfere with our main use upstairs.

Everything seems to be working fine and from what I've read I've done it right. However on further thought, my question is how do traffic limits work? I.e. Since there is only one network showing, how do I know my devices are not being affected by the limits? Or if they are working at all?

If I have set up the traffic limits wrong or if they will not work in the way I've intended, does anyone have any suggestions for how I can go about this?

Many thanks