Shell commands permissions problem

Hi everyone,
My setup: HA installed on docker running on a homesserver (MiniAir11) on OMV. A Raspi3 I have libreelec running kodi. I start the Raspi3 via HA controlled power plug.

My goal: I want to shutdown/reboot kodi via HA. Reason: during shutdown a small skript on the Raspi3 runs to turn off the projector via IR interface.

My steps I’ve done:
I added the .pub key in libreelec to autorized_keys. Now I’m able to ssh my Raspi3 from inside the HA container after root login successfully.

But when I create the following command in configuration.yaml (exactly this string works via console perfectly as root user):

shell_command:
  reboot_raspitv: "ssh [email protected] reboot"

… and I run it, I get the error:

Host key verification failed.

I stepped back and tried a simpler task and added:

shell_command:
  testmkdir: mkdir testauto

… and I get the error:

"mkdir: cannot create directory ‘testauto’: Permission denied

The HA docker compose comes from linuxserver and there I use the same user for each container I create (PUID 1000, PGID 100).

I’m sure I missed something very basic but since I’m not good in the permission topic and after a long search and nothing suitable found, is there anybody out there to point me in the right direction? Thanks and cheers,
Flo

Edit: SOLVED!! I found the right way to go here. After restarting the HA container it worked: