So I obtained a Hauppage WinTv HVR 930C DVB C USB TV, installed the PVR TVheadend from the app store and configured it (successfully, I think) with the web interface.
Then activated Tvheadend HTSP Client over settings > addons > PVR clients and activated PVR at settings > TV.
Now every 8 Seconds a message pops up “Tvheadend HTSP Client : connection lost”.
Here are the files:
http://paste.osmc.io/hijonacuxe
Looking forward to your ideas!
Wolf