Channel without ventilation or with?

Right. But for me, it's about a possible ventilation.

Hi, I don't think you need an additional vent for that diameter (that should be around DN 160-200?). But I don't know how quickly the shaft fills up at your place. If the water level goes above the pipe, then it drains worse without ventilation. But then with that arrangement, you have the problem that there is a backflow to the downpipes of your house. So that's a problem anyway...