Missing channels on our satellite system - Who knows this?

I'm not really an expert in the field, but in my opinion, you need an LNC with a multiswitch and not an LNB.

LNB is correct. What could be the case, however, is that instead of a Quattro LNB, a Quad LNB is installed. That could possibly also fit with the described problems. Maybe also consult a forum on the topic of digital television. Links are forbidden here, even if they would be so useful.

It would be most helpful if you could send us the designation of the LNB and Multiswitch.

I do not get the impression that the OP is still interested in a solution to his problem at all.

Could it have anything to do with the HD channels?