Try connecting the Roku directly to the TV. What does it do there?\n\nI did connect the Roku directly to the TV, just to see what would happen. The Roku continued to deny the existence of 4K in my system. But, then I found the setting in the TV itself that enabled 4K. Now, the Roku is connected to my receiver and finally working fine, displaying in 4K.\n\nBTW, there’s yet another setting in the TV that controls whether the stereo speakers built into the TV are used or if external speakers, like those in my 5.1 surround setup, are used. It seems to apply on an input-by-input basis. Just another wrinkle.\n\nAnyway, thanks for the tip.