For buyers contracting authority
Reach for 48823000 when the thing being bought is storage-and-serving capacity: a file server, a NAS box, or the disk array that holds shared data and backups. The judgement call is against the neighbouring server codes. If the box exists mainly to run applications or general workloads, Computer servers (48822000) is the closer fit; if its defining role is network services and routing of traffic, Network servers (48821000) fits better.
A second boundary worth setting deliberately: web servers (48825000) front-end web applications, while a file server stores and hands out files internally. Where a single procurement bundles compute, storage and networking into one data-centre refresh, set the primary CPV code by the dominant deliverable rather than by the whole bundle, and use lots to separate the strands an authority wants priced independently.
Because storage purchases tie an authority to a hardware platform and its support contract for years, the specification should pin down capacity, protocols and warranty terms early.