Upgrade my Synology NAS for faster web facing VMs + Docker - Advice

I need to upgrade my Synology NAS to one that supports ECC ram, and can also run my VMs and Doker containers faster, since I run web facing apps for a business, and would like some advice.

I currently have a 920+ with 2x4TB WD Red HDDs + 2x8TB WD Red HDDs (all 4 in one storage pool and one volume, using SHR with data protection for 1-drive fault tolerance). I also have 2x1TB NVMe SSDs (WD Red SN700) read-write cache in Raid 1. Also, 1x16GB DD4 2666 MHz non-ECC unbuffered ram + the 4GB embedded ram, so total 20 GB. I have a symmetrical 1Gbps internet service.

The 3 primary things I need to achieve are:

  1. ECC memory support
  2. More RAM as I am currently maxing out (constantly at around 80-85%)
  3. Web apps running on VMs (Mailcow, and two instances of ERPNext) and Docker containers (Nextcloud-AIO, Portainer), need to be faster. Currently the web apps, which use SQL databases running in same VMs (ERPNext which uses MariaDB in same VM) are kind of slow, i.e. when you click on the web page it takes several seconds to process and refresh page with results.

The DS1621+ seems to check the box for ECC, more RAM (32 GB), plus it supports NVMe storage volumes if that’s a route I should take to improve response of the web apps.

Some questions I have:

A. Is it possible to use the 2x1TB NVMe drives as both Storage Volume, and also read-write cache? Or only one of the two?
B. Should I configure the NVMe SSD cache as read only?
C. Should I add two SATA SSDs and create a separate storage pool/volume and install the VMs and persistent Docker volumes there?
D. Should I configure the NVMe’s as storage pool/volume and install the VMs and persistent Docker volumes there?
E. Should I add two SATA SSDs and configure as read-write, or read-only cache?
F. What would be best combination/configuration to achieve faster VMs + Docker apps response?

Any suggestions and recommendations to achieve faster response times for the web apps are very welcome, as well as anything else I may be missing.

Thank you.

It may be time to move your VMs off your NAS to a dedicated server. There are plenty to choose from in a wide variety of form factors that will cost less than a new NAS and provide more scalability for future growth. Cloud hosting may also be a consideration.

The nice thing about VMs and containers is how easy it is to move them to new hardware