Passage house/garage (~2.6m) occasionally childproof lock

Actually, a wooden plank or something similar would have to be mounted at the bottom edge of the net so that the thing cannot simply be lifted up and crawled under.

No, I meant, like in the football goal, not tight. So not just touching the ground, but preferably twice as "high". Then it becomes a slapstick routine to "lift" the loosely draped net.

Laser alarm? Power cable?

How old is your son?

How about children

Wire mesh gates are really even more expensive than I expected after initial research

Where are you looking? So for 200 euros, it is done there.

1m high.

temporary crowd control barrier example 2.5m

Badminton, volleyball net "empty words"

And what will it be now?

.... Maybe one could also put up a higher puppy playpen.