Just as you cannot build a bridge without engineering or it would fail; so too is network engineering important in order to have a functional, reliable network.
A network engineer handles all of the “plumbing” for a company’s Internet connections, remote offices, computers and telecommunications requirements or what is now known as I.C.T. (Information Communication Technology), connecting offices with available links and communication technologies in a way that provides for the amount and type of traffic that is required by the client without wastage with redundancy and growth factored into the engineering, hooking them up on to the Internet, and configuring all internal systems such as net routers, switches, servers workstations, Phone systems, phones, phone lines, VoIP services, remote teleworkers, remote servers, WiFi, cloud solutions and firewalls.
A network engineer has to be able to think through problems, limitations, specifications, requirements and understand how systems integrate. A lot of the time is spent planning, calculating and, finally, formulating a spec, design and costings.