Best ReadyNAS Setup for Secure Resume Storage?

All ReadyNAS are end-of-life with an OS that has not had a "real" update in years.  They can no longer be purchased new, and the warranty (for those few units still covered) isn't transferrable.  The only available support is right here, from fellow users.  It's Linux core is receiving no new updates (security or otherwise) and hasn't for years.  The former "ReadyCloud" remote access was taken down some time ago. 

In short, look elsewhere unless you are already invested in ReadyNAS for other purposes, in which case I'd expect you'd already know the answers to most of your questions. (A secure alternative to ReadyCloud being the exception.)