Filebrowser, can‘t open images in the www folder (err. 401) from the app, from browser it works

I have HA running on a Synology in VM, and if I try to open an image from inside the www folder directly from the companion app (different devices, different browsers) a browser window opens and I get a 401 error but if I am logged in to HA via the browser it works. Is there somewhere something to configure that it will work from the companion app?

Failed to to call /ingress/validate_session -
17:13:54 – (FEHLER) Home Assistant Supervisor
/ingress/validate_session return code 401
17:13:54 – (FEHLER) Home Assistant Supervisor

Now that I have not found a solution in the German-language forum either, I have solved it with a workaround:
In the configuration.yaml

  move_latest: ‘mv $(ls -t1 /config/www/folder/*.jpg|head -n1) /media/’

and in automations.yaml after sending the image via notify…

- service: shell_command.move_latest

The image is then available for viewing in the media folder and I can also conveniently delete it there.

This is not the solution to the actual problem, but it is a workable compromise for me.