I don't know the answer to this, so I think that you should assume that TV Server does not support 4K TV broadcasts, until such time as someone tries it and finds that it does work.just checking TV Server is capable of 4K streams.
Belgium
"for some reason"my tuner can't tune it for some reason
I can confirm TV Server is capable of 4K streams. There is a free-to-air "SES UHD demo" channel on Astra 19.2°E which works perfectly fine on my system. It broadcasts using a HEVC (H.265) 3840x2160 video stream. I use a TBS 5520SE tuner to receive this channel.just checking TV Server is capable of 4K streams