damn, are you trying to pull a coup on your family's internet?
anyway, either you do it directly on the router or you will have to use an access point. the only way i can think of that could work without messing with the router is to use a firewall device (or pc with pfsense or something like that).
so the main device we can forget it has got this bandtwidth option disabled
but I have got TP link Archer A7 currently set up as an acces point
but once it's turned from router mode to access point mode I can see QoS options in the menu disappeared, also it has got no advanced options anymore, as if they were hidden
Sorry was offline.
The main router provided by the ISP might not have QoS(usually down).
You can do 2 things:
1) Bridge the ISP router/modem(if u have cable modem u will have to bridge the modem since it is difficult to replace it). Then u will enable TPLink A7 in router mode.
2) Run network in the network. Basically u will connect ur TPLink A7 to the existing router, Then u will disable wlan on main router and only run one lan cable to TPLink A7 so that u can establish connection