trying to set up an iptv box to my roku 3900x but unlike my Tcl roku there is option to choose a tv input under the system menu.
simalar to my tcl roku, i setup a sattelite box with a link button on my home screen, I should have the option of adding different imput sources
Only Roku TVs have inputs. There's no way to add an input to a 3900. You'd connect that device to the TV that the 3900 is connected to, not the 3900.