Redirection with 404 is not working

After using "all" quite while I feel like we need to improve performance of the site and one of them might be redirections.
It works well with redirections: "all", but stil cannot figure out how 404 works.

redirections: "404" or
redirections: ["404", "/stockholm/tandlakare-alvsjo/"], does not work at all.
Any suggestions?

But works with redirections: ["404", "301"] :thinking: