Device List on Gateway vs Xfi App - and QoS

So when I go directly into my gateway through a web browser using the http://10.0.0.1 and look at the device connected list and then compare it to the device list on the xfi App, there are devices on there that are showing connected, but Xfi list shows paused, and then there are two devices that look just like MAC addresses that are connected that don't show at all and I can't figure out how to block or pause them.   Also is there anyway to prioritize a devices internet usage with Xfinity, if I want like a game console to take priority over everything else?