Hello. I've just built my first NAS using a Raspberry Pi 3 (Raspberry Pi OS Lite), a 2.5 HDD, and OMV software. I installed Docker and Portainer for Syncthing software. My system works fine, and I'd like to use it for backups of files from my computer. My tests were successful, but before I start keeping my data on it, I'd like to know how to protect it. I was certain that with the default configuration, the NAS 'is closed' in my local home network, but Syncthing pinged and synced with my smartphone connected by mobile data without any problem. Well, it's a useful feature, but I realized that files on my hard drive can be accessed from the 'outside.' What are the mechanisms, and how can I secure my NAS from being hacked? I've read about brute force attacks, so I turned off SSH in OMV and put strong passwords on the software. What else should I do? Or maybe I'm wrong, and my NAS is safe? I would appreciate an explanation of the risks and security methods in a relatively simple language 