Cannot run ssh shell command from hassio gui


I have been reading for several hours and cannot find a solution to my problem (or a good explanation). I am trying to run a shell script to shutdown my other server. I have installed the terminal add-on and can ssh into my other box using the ssh key as root from this addon, but when I try to execute a command in hassio it fails with permission denied and no password.

Why is in not using the key I copied over from the terminal. From what I understand, the Hassio is running as root in the container, and when I ssh into the box it shows the key to be in the root folder. Where does it need to be for the gui to recognise it and use it to ssh into the target box?

I have looked to see if there are other users in the terminal window, but root is the only one recognised, so what do I need to do?

Thanks in advance

Thank you for your help. It does make me question why the documentation I was following doesn’t mention it. Must be out of date, like a lot of docs.

What documentation were you following?