I know, in any other level it works as expected, duplicating the signal to both routes.
But in Protocol 7, the splitter works like a filter to the opposite type, and just destroys every signal.
Let me get you this link to a video about me almost solving this level:
https://videotourl.com/videos/1789631866212-06add87f-a627-4f3f-a25d-205c070ea14e.mp4
(also sorry its like 16 Mo which is why it cant be posted directly, i tried ;u;)