im using Plex now on different devices ( LG WebOS, XBox, Amazon Fire TV ) and there is still no option to change a channel by Remote Device. You have to go back to EPG to choose another channel, i wished to be able to change the channel eg. on LG WebOS by clicking programm up /down buttons. Or maybe open a windows where you can switch the channel without leaving the running program.
There’s already an existing suggestion discussing an option to improve channel navigation (e.g. up, down, back to previous channel…). I suggest you comment/vote in that thread in order to help us avoid distracting or cannibalizing votes. Unless I’m missing some unique aspect of your suggestion I’ll close this thread as a duplicate.