Originally Posted by
Niya
TX is transmit/send, RX is receive, and since you're viewing the router side, you're correct that the chromecast is constantly downloading. Maybe someone started a video stream but forgot to stop it before turning off the TV or something like that.
And that a phone shows constant traffic should also be normal. Most apps (social media, mail, weather etc) keep running in the background and check for new stuff to display/report every once in a while. Though that shouldn't cause much traffic.