Limiting bandwidth usage by device?

[Playborg]

how do I limit bandwidth by device? 

I want to restrict XboxOne to 50Mbps or lower - as I keep going over my monthly bandwidth plan I have with my ISP.

I have already downloaded Netgear Genie

[michaelkenward]

There is support for the WNR3500Lv1, including a manual, somewhere at the end of this link:

>>>> WNR3500Lv1 | Product | Support | NETGEAR <<<<

It looks like this router does not support either QoS, one way of prioritising network traffic, or a traffic meter, which would warn you if you hit the limit.