I am surprised you didn’t find security to be a key issue with network attached storage.

* Physical security. On 1, in case you have a synology NAS, it does not offer full disk encryption. Its folder encryption also has a number of problems. Your mitigation here (back ups) doesn’t help with loss of data to others.

* Network security. In addition to the physical security, consumer NAS devices don’t do enough in network security. Some of them come with closed source operating systems with a lot of potentially dangerous sharing and networking features. The code is often not reviewed.

On 2., you can use ZFS or btrfs, and they offer good features, but come with separate set of problems.

I spent some time on NAS security and couldn’t find a good solution. I thought I better let Amazon and google to secure my data.