Sorry for my reply. I'm only an F-Secure user (their home solutions); so, it is only my own unofficial feelings.
While some cyber security companies does offer specific solutions for NAS-related things (in general, for 'business'-users) - I'm not sure that there are some solutions for home users as server security for their NAS (or certain model). If 'not' and there is available something by some company -> I think that F-Secure (currently) does not offer such 'home' solution. For except, their 'secure router' -> https://www.f-secure.com/en/web/home_global/sense -> as complex solution for Home users with 'smart' (extended/advanced/connected) devices (example of set up SENSE and Synology solution).
OR does your ask is about something like potential security suggestions and tips for NAS 'security' (synology ds214)?
Or does your ask is based on certain specific requirements or thoughts? For example, do you want to be with certain abilities/features (like to scan storage or so)?