[TheSaint67]

I am running Kodi 19.x on my Nvidia Shield Pro and I am quite happy with it.  My 6tb WD My Cloud decided to call it a day, so I am looking into getting a new file server.  the NAS should be able to read/write from MAC, LINUX and Windows systems.  I want to be able to read and write to the NAS and of course have the Shield stream the videos to the TV nicely.  I feel like Synology may be the way to go, but also think a RAID system may be unnecessary.   I guess 8tb or so would suffice.

What qualities should the Server have?  CPU, memory, access speeds for 4k video delivery, etc.  

is DNLA important on the file server for Kodi to work? I didn't get that impression in the past.

Thank you in advance.

[Klojum]

but also think a RAID system may be unnecessary.

Based on what? If a single harddisk crashes, most if not all data is gone. In a simple RAID 1 setup, the other harddisk will still have the data.

PC clients connect to a file server via a file protocol, of which the most popular are SMB, NFS, FTP, etc... As long as your client can connect to the file server, there isn't a problem.
When you are setting up a network for multiple Kodi clients, then it's best to also use a centralized database for all metadata from all movies, tvshows, music, und so weiter. A NAS can do that.
You will have to choose a network file protocol that can run on/from every Kodi client, otherwise syncing on all Kodi devices will not work.

What qualities should the Server have?  CPU, memory, access speeds for 4k video delivery, etc.  

Yes :-)

Most new NAS devices will have no problem serving your video files as long as the rest of the network is upto par as well. Wifi connections can quickly ruin your viewing pleasures.

is DNLA important on the file server for Kodi to work? I didn't get that impression in the past.

It still isn't (IMO), but your situation may be different from mine.

[TheSaint67]

but also think a RAID system may be unnecessary.

Based on what? If a single harddisk crashes, most if not all data is gone. In a simple RAID 1 setup, the other harddisk will still have the data.

The video content KODI will access isn't worth backing up.  Surely annoying to lose data and replace, but the videos aren't there for longevity.  Just watch and delete.  The audiofiles I will have backed up on another system.  

Danke.  I believe I will grab a Synology DS220+