This NAS is useful for me in many ways. The first and most important one is that it holds all my backups. For it to last with more and more files each year, I filled it with four hard drives with a capacity of 3TB each. To protect the data even more, I use the recommended Synology Hybrid RAID (SHR) that is quite equivalent to RAID 5. It uses one hard drive where it's not possible to store anything to guarantee a one-drive fault tolerance. I access it via SFTP when I'm working on Linux, and via SMB when I'm working on Windows.

Log Server

One of the main use I have for this NAS is that it is my log server. For every Linux machine I have, as well as my firewall, every log is retrieved via rsyslog to the log center. I used to have a Raspberry Pi with loganalyzer for that but I had to change due to security concerns regarding this tool.

Here's what the log collecting center looks like :

As you can see, we have a graph corresponding to the number of log entries sent to the NAS, as well as the last 50 logs displayed for every machine (I blurred for security purposes).

There is also a menu that lets me look at everylog and filter them by machine.

Here's what this menu looks like :

After selecting a sepcific machine, we can also slected the type of logs we want to display. This helps when you have a lot of them and want to easily apply a filter.

Here's what this menu looks like :

Media Server

I also use it as a media server. With the DLNA/UPNP protocol every machine connected to the network and compatible with these protocols can play media from the NAS directly, as long as the files are indexed by the NAS and the media server is configured properly. This is very useful as there is no authentication involved.

Here's what it looks like on my TV :

Here I just have to select it and I can browse and play the indexed media from my NAS.

I also have an Android TV device where I installed KODI to play media with more functionality than what my TV offers.

Here's what it looks like on KODI :

After configuring KODI properly, I can play media from my NAS.

PXE

This NAS is also a PXE server. I work with many machines, and always making bootable USB drives for small utilities like GParted, Clonezilla, and other ones that I often use, is not worth the time and effort it takes, compared to boot on the network card. PXE is a bit complicated to configure though, there are special files to have for network boot, which are specific to each operating system and utilities, and the parameters put in the default configuration files also vary.
This project is not yet terminated. I would like to have some Linux and Windows operating systems to boot in addition of the tools. Right now, not everything boots, but the menus are created and working.

Here's what the PXE main menu looks like :