I had been bought samsung q7f 2 days ago,but when i speak to tv that “channel(number)”it shows “i can’t set that mode”.but other commands like volume up/down,channel up/down is working?
Same problen here on a month old UE43NU7400UXXU. It appears to be a problem with numbers, though probably not limited to. If I say "Channel 101", (or just "101" which also used to work) then what I said is briefly displayed followed by the error message. If I say "Volume Up", than that works, but "Volume 6", again briefly displays what I said, then the error message.
Edit: 4 hours after my comments above, and without changing anything at all on the TV, the voice commands started working again. I can only assume that the problem was with Samsungs servers that process the voice recognition.