I require a new NAS.
I need a NAS to run some Docker or Vms, so it needs to be AMD or Intel CPU. I also require the nas to have SSD Caching and have 10GBit SFP+ nic.
AMD or Intel CPU
2x M.2 or 2.5" SSD slot for SSD Hot Storage for cache and VMs.
4x 3.5" HDD slots
Expandable RAM 8GB+
10Gbit SFP+ Port
Also full HDD Encryption.
Now I hope I can get a nas like this for $1200 below.
A Synology DS1618+ maybe? You need to add in your own SFP+ card (or alternatively a NVME card) but you can run two 2.5" SSDs for a write/read cache.
The processors in most NAS units are going to be pretty poor, so if the primary purpose is going to be VMs you may need to build your own system.
Also:
I haven't checked in a while, but you used to be able to pick up cheap SFP+ cards on eBay. I'm running Mellanox cards in my Synology / Desktop.
A SSD cache isn't going to help with media stuff, but will be useful if your workload have a lot of predictable small reads/writes.
Edit: If you only want high network speeds because a bunch of PCs need to access the NAS then link aggregation might be enough with the 4x 1GBe ports. (You won't get 4Gbit/s to one PC, but you could get 1GBit/s to 4 PCs at the same time).
Edit2: Synology doesn't have full disk encryption, so I think you're only other option is QNAP like the TS-473.