Solution needed: - Downpipe Leaf/Debris Filter

I think you will have to die one death. I would consider replacing a part of the downpipe with a corresponding dirt collector part. Maybe you could also connect a rain barrel there right away.

As already mentioned, you should find the appropriate item under Schmutzsammler or alternatively Laubabscheider - however, not to be installed without modification to the downpipe.

Ok thanks, thought I could avoid that. Thank you very much for the suggestions

You can bend a makeshift solution from hexagonal wire mesh aka chicken wire in front of the last opening you can reach.

Helps on my balcony against mice that want to climb up and leaves that want to go down the drain.

Does it hold? Do you have a pic?

where and how does the pipe end? normally in a soakaway box, which has a sieve.