If you are connecting with WiFi it's 100% there's a router in that box.
What sort of freeze? Today it's still happens a lot that it takes time for the video to get from the web to the devices with a freeze then it starts playing. If the freeze is forever then it's usually the computer and not the networking.
YouTube TV is also very new compared to say Netflix. Does Netflix work fine?
I want to understand if I need a router or not. I am with time warner as my cabel and I believe all I have is a modem no router. I have wi-fi on two computer a laptop an I pad and 2printers I just set up youtube tv and at times it freezes would adding a router or something else to protec reception

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