selfprivacy.org.app/assets/markdown/how_fallback_ssh-ka.md

Login as root user to your server and look at the contents of the file /etc/nixos/userdata/tokens.json

cat /etc/nixos/userdata/tokens.json

This file will have a similar construction:

{
    "tokens": [
        {
            "token": "token_to_copy",
            "name": "device_name",
            "date": "date"
        }

Copy the token from the file and paste it in the next window.