When to Run Ethernet Instead of Wi-Fi — and How to Do It Cheaply

Wi-Fi is a shared, half-duplex medium that every device in the house and several next door are competing for. Ethernet is a private, full-duplex link that does not care about your neighbour’s microwave. For the handful of devices that never move, running a cable is still the largest single improvement available to a home network — and it is usually cheaper and less invasive than people assume.

Which devices actually benefit

Not everything needs a wire. The test is whether the device is stationary, whether it moves sustained traffic, or whether it is latency-sensitive.

• Desktop computers and workstations. Never move, often transfer large files, and taking them off the air frees airtime for everything else.
• Game consoles and gaming PCs. Latency and jitter, not throughput. A wired link removes an entire category of intermittent problems.
• NAS boxes and home servers. These saturate a link by design. On Wi-Fi they saturate the whole band.
• Wi-Fi access points and mesh satellites. The best possible use of a cable. A wired backhaul turns a mesh from a chain of relays into a set of independent radios.
• Televisions and media streamers in a fixed cabinet, especially where the cabinet itself is attenuating the signal.
• Work-from-home video setups, where consistency matters more than peak speed.

Phones, tablets, laptops and smart-home sensors stay wireless. That is what wireless is for.

Cable categories: what each one really supports

The relevant IEEE standards are narrower than the marketing. IEEE 802.3bz-2016, published on 18 October 2016, defined 2.5GBASE-T and 5GBASE-T specifically so that intermediate speeds could run over cabling already installed in buildings. IEEE 802.3an-2006, published 1 September 2006, defined 10GBASE-T for up to 100 m of balanced twisted-pair structured cabling.

The famous 55-metre limit for Category 6 is not in the headline scope; it comes from the task force’s work on alien crosstalk, the interference between adjacent cables in a bundle. A July 2005 presentation to the 802.3an task force lists 55 m for unscreened Category 6 with no alien crosstalk mitigation, and 100 m for augmented Category 6. Category 6A exists precisely to make 10GBASE-T work at the full distance.

Cable	1GBASE-T	2.5G / 5GBASE-T	10GBASE-T
Cat5e	100 m	Yes — the case 802.3bz was written for	Not specified
Cat6	100 m	100 m	Limited reach unscreened; ~55 m without alien crosstalk mitigation
Cat6A	100 m	100 m	100 m

What to buy

For almost every house, Cat6 is the right answer: cheap, flexible enough to pull, and comfortably capable of the 1 Gbps and 2.5 Gbps links that home equipment is only now starting to ship. Cat6A is stiffer, fatter and harder to terminate, and it is worth it only if you genuinely intend to run 10 Gbps over a long run and want it certified. Cat5e is fine for a short run to a console and is often already in the walls of houses built since the late 1990s — check before you buy anything. Ignore anything sold as “Cat7” or “Cat8” for residential use; neither is recognised in the TIA structured cabling categories that home equipment is designed around, and neither solves a problem you have.

One caution: buy solid-copper cable, not copper-clad aluminium. CCA is cheaper, has higher resistance, breaks when bent repeatedly, and behaves badly when carrying power.

Power over Ethernet, briefly

PoE sends DC power along the same cable as data, which is how you put an access point on a ceiling or a camera under a soffit without an electrician. The Ethernet Alliance’s overview of 802.3bt gives the budgets by type:

• Type 1 (802.3af) — up to 15.4 W from the source, about 13 W available at the device, over two pairs.
• Type 2 (802.3at, “PoE+”) — up to 30 W from the source, 25.5 W at the device, still two pairs.
• Type 3 (802.3bt) — up to 60 W over four pairs, with up to 51 W at the device.
• Type 4 (802.3bt) — up to 90 W from the source and 71.3 W at the device, four pairs required.

A home access point is typically a Type 1 or Type 2 device. That means a single inexpensive PoE injector — a small box that sits between your switch and the cable — is enough. You do not need a PoE switch to power one access point.

Getting a cable across a finished house

This is the part that stops people, and it is more tractable than it looks. In rough order of how much drywall you have to disturb:

1. Reuse what is there. Old coaxial, telephone and alarm cable often runs exactly where you want to go. Tape new cable to the old one and pull it through as you withdraw it.
2. Go through unfinished space. Basements, crawl spaces and attics let you travel horizontally without opening a single wall, then drop or rise at each end. In a house with an unfinished basement and a ground-floor office, this is a ninety-minute job.
3. Use exterior routing. Outdoor-rated cable along a soffit or under siding, in through a drilled and sealed penetration, is common practice and completely reversible.
4. Run flat cable under trim or carpet edges. Ugly at close range, invisible at normal range, and genuinely rentable-friendly.
5. Fish inside a wall cavity as a last resort, with fish tape and a stud finder, accepting that you will patch something.

Terminate into keystone jacks and wall plates rather than crimping plugs onto solid-core cable. Solid conductors and RJ45 plugs are a poor match, and a jack plus a short factory patch lead is more reliable and easier to test. Keep the whole run under 100 m — in a house you will not come close — and keep it away from parallel mains runs.

The wireless-free alternatives when you truly cannot drill

MoCA over existing coax

If your home has cable television outlets, it already has a high-quality shielded transmission line in the walls. MoCA adapters turn that into Ethernet. The MoCA 2.5 specification is rated for 2.5 Gbps MAC-layer throughput with average one-way latency under 2.5 ms, using spectrum between 400 and 1675 MHz — well above the frequencies used by television or DOCSIS service, which is why it coexists with them.

You need adapters at both ends, the two outlets must be on the same coax tree, and if you have cable internet you should fit a point-of-entry filter so the signal stays in your house. It is the best non-Ethernet option by a wide margin.

Powerline: manage your expectations

Powerline adapters modulate data onto mains wiring. They are worth trying and worth returning. Real throughput depends on the age and topology of the wiring, and on whether the two outlets sit on the same leg of the electrical panel — cross the legs and the signal has to couple across the panel, losing most of its strength. Motors, dimmers and switching power supplies inject noise. Plugging an adapter into a surge-protected power bar will usually kill the link entirely, because the protector filters exactly the frequencies the adapter uses. Advertised rates are aggregate physical-layer figures that no installation reaches.

Use powerline when you rent, cannot drill, and have no coax. Otherwise use MoCA, or a cable.

The practical version

Pick the two or three devices in your home that never move and carry the most traffic — very often a desktop, a console and one Wi-Fi access point. Check the basement, attic and existing coax before you plan anything. Buy solid-copper Cat6, keystone jacks, a punch-down tool and a cheap cable tester; the whole kit costs less than a mid-range mesh node. Wire those devices, leave everything else on Wi-Fi, and note that removing three heavy users from the air improves the wireless network for every device you did not touch.