For buyers contracting authority
Pick 72710000 when the work is bounded to a single site or campus: structured cabling, switching, wireless, on-site firewalls, and the support that keeps the local network running. The cleanest test is geography. If the deliverable lives inside one building or a tight cluster of buildings, this is the code; if it carries traffic between separated sites, that is Wide area network services (72720000).
The boundary that trips contracting authorities is the equipment-versus-service line. Buying the switches, routers and access points as goods points to Network equipment (32420000); buying the design, installation, configuration and support of the local network as a service points here. Where a single contract bundles the hardware with the rollout and ongoing support, tag the primary CPV code by the dominant purpose, which on managed-network deals is usually the service.
One more neighbour to keep separate: Data network management and support services (72315000) is the better fit when the scope is purely run-and-maintain of an existing network, with no build or upgrade element. Reserve 72710000 for the local-network work itself, build, upgrade or support, scoped to the site.