Tvheadend

So I bought DVBSky T330 DVB-T2 / T / C and I have quite an unusual problem:

If I connect a splitter to the antenna, this happens to me:
I have only TV HAT connected to the splitter and I can play programs from it without problems, but when I connect the T330 to the splitter, playback from the TV HAT stops as if the T330 has stolen the TV HAT signal. If I disconnect the T330, playback from the TV HAT starts again and continues smoothly.

When I have both tuners connected, the T330 tunes the muxes, but the TV HAT doesn't seem to have a signal.

Have you ever seen anything like this?

I will be glad for any advice, maybe I missed something in the settings where this behavior can be influenced.

Thank you