Below are the production-proven specifications of servers, minimal for reference.
Main Server (Application Server):
always up;
RAM — 8 GB;
CPU — quad-core Intel-compatible;
OS — Linux x64;
static external IP address;
accessible on a TCP port within LAN (default port 45430);
TCP ports by default and depending on installation type 45431 (file storage), 4040 and 4080 (HTTP), 80, 443 (HTTPS), 5432 (Memoria) open and forwarded to Internet.