Buying an Ethernet switch: count the uplink before the spare ports

For several wired devices sharing a router connection, plan for an Ethernet switch and count the router connection as one of its ports. An eight-port switch normally leaves seven device connections when one port links it to the router. The printed port count is not automatically the number of new computers you can add.

Give each connection a job

A switch connects devices within a network; it is not a replacement for every job performed by a router. TP-Link describes switches as forwarding Ethernet frames according to destination addresses. For a simple home-network expansion, the useful question is how your existing router, switch and wired devices will connect.

Do not buy by the word “splitter” alone. Some powered products sold as Ethernet splitters perform the network-expansion job: TP-Link's EH310 documentation, for example, requires power and reserves a port for the router or switch connection. Other adapters may serve different purposes. Require a clear diagram and explicit simultaneous-device support rather than assuming a passive socket adapter creates extra independent network ports.

The port-budget worksheet

Write one line per cable that will occupy the new switch:

• Router/uplink: usually one port in this simple layout.
• Devices now: one each for the desktop, console, printer, NAS or other wired device.
• Planned additions: only items you realistically expect to connect.
• Other links: any additional network connection that consumes a port.
• Total: add those lines and compare with the usable port count.

Worked example: one router link, one desktop, one console and one printer use four ports. Adding a NAS and keeping one connection spare gives a six-port requirement. A five-port unit fails that plan once the router link, four end devices and one spare are included. An eight-port unit leaves three physically unused ports: one reserved spare and two additional ports.

Put the speed beside each cable

Record the stated port rate for the router, proposed switch and each important device. “10/100” is not gigabit. Do not read the sum of several ports or a switching-capacity figure as the speed of one connection. Nor does a faster switch increase the broadband service you purchased.

Consider local transfers separately from internet use. Someone copying large files between a computer and NAS may care about their wired path even when the internet connection is modest. A 100 Mbps switch port cannot provide a gigabit link; the complete path must support the requirement.

A concrete listing to assess

For a modest 10/100 network, compare the eight-port 100M RJ45 unmanaged switch with your worksheet. Its listing specifies eight adaptive 10/100 Mbps ports and a plug-and-play design. This is not a gigabit recommendation. The text does not establish PoE output or the supplied UK power arrangement, so do not assume it powers cameras or includes the power equipment you need. Confirm the package and power requirements before purchase.

Keep the scope simple

This worksheet is for choosing hardware, not configuring a managed or business network. If you need VLANs, PoE, specialised uplinks or changes to an organisation's network, get the responsible administrator's requirements first. Extra sockets are useful only when their function, speed and power needs match the job.

Sources and scope

This is a specification-based buying guide, not a hands-on product test. Product details were checked on 7 November 2026.

• TP-Link: switch and router distinctions
• TP-Link EH310 installation guide
• TP-Link: documented 10/100 port example