A LAN cable is faster than WiFi — here is the real reason
WiFi and a LAN cable are not two speeds of the same road. Test your own line both ways, see what a shared radio actually costs, and know when one cable beats an extender.
The speed test on your laptop says one number. You plug in a cable, run the same test against the same server, and the number jumps. Same plan, same room, same device, same minute. Nothing was upgraded, so what changed?
The delivery method changed. WiFi and a cable are not two speeds of the same road — they are two completely different ways of getting data to your screen, and one of them has a hard physical limit that no plan upgrade and no newer router can remove.
WiFi is one conversation at a time
Imagine a meeting room with a single microphone. Everyone in the room wants to speak. Only one person can hold the microphone at a time, and everyone else waits, listens for a gap, then grabs it. That is WiFi. The technical name is a shared medium with carrier sensing, but the microphone picture is close enough.
Two consequences follow, and both explain the number on your screen:
- Every device on the same channel waits its turn. Your phone, your TV, your child's tablet and the neighbour's router all take turns. When more devices join, each turn gets shorter, even if nobody is downloading anything big.
- The radios take turns talking and listening. WiFi is half duplex — it cannot send and receive at the same instant. A cable is full duplex, so a download and an upload travel in opposite directions on separate wire pairs and never collide.
On top of that comes overhead: every WiFi frame carries management information, waits for acknowledgements, and backs off when it hears something else. The rate your router app shows for a connected phone is a link rate, not a data rate — the payload that actually reaches your screen is a fraction of it.
The test that settles it in ten minutes
Do not trust a general claim about WiFi being slower. Measure your own line, both ways, in the same conditions.
- Pick one device — a laptop with an Ethernet port is easiest. No port? A USB-C to Ethernet adapter works, including on most phones.
- Stand one metre from the router, on WiFi, and run a speed test. Write down the download, the upload and the ping.
- Plug in the cable to the same router, turn WiFi off on that device, and run the same test against the same server.
- Compare the ping, not just the speed. Ping and jitter are where the gap is loudest, and they are what video calls actually feel.
If the cable number is much higher and the ping much lower, your WiFi is carrying overhead, not a bad plan. If the two are almost the same, your WiFi is fine and your bottleneck is somewhere else — inside the house wiring, the router's own CPU, or the provider.
What each method is actually good at
| WiFi | LAN cable | |
|---|---|---|
| Speed ceiling | Shares one radio with everything nearby | Each device gets its own full-speed link |
| Consistency | Drops with walls, distance, neighbours, microwaves | Same speed all day, at any hour |
| Ping and jitter | Higher, and it moves around | Low and flat |
| Adding devices | Each new device takes a slice of airtime | No effect on other devices |
| Cost and effort | Already there | Cable, clips, maybe a long drill run |
| Best for | Phones, tablets, guests, anything that moves | TVs, consoles, desktops, work laptops, cameras |
The cause most people skip
When WiFi feels slow, the usual suspect list is the plan, the router model, or the ISP. The cause that gets skipped is how many things are quietly using the radio — and how much of it is not a download at all.
A smart TV streaming 4K, a CCTV camera uploading constantly, a tablet syncing photos, a game console downloading an update in the background: each one holds the microphone for a while. None of them individually looks like much. Together they turn a fast connection into a queue, and the queue is what you feel as "buffering".
This is the part that makes a cable worth more than people expect. Plugging in the TV and the console does not make the WiFi signal stronger. It removes the two heaviest talkers from the room, so the phones that stay on WiFi get a bigger share of every turn. The whole house usually feels faster, and nothing about the WiFi was changed.
There is a second, cheaper cause: your router's LAN ports. A router sold as gigabit can still have a 100 Mbps port, and a single damaged or badly crimped cable will negotiate down to 100 Mbps on its own. Before concluding that a cable is not worth it, check what speed the port actually came up at in the router's device list.
Spend in this order
- Free first. Move the router out of the cabinet, off the floor, into the open. Use a cable you already own for the TV before buying anything. Check the router's device list for the link speed on each wired port.
- Then a cable run for the devices that never move. One long cable to the TV or the work desk often fixes more complaints than an extender does.
- Then an access point on the end of that cable if a room is still weak — a cabled access point keeps full speed, while an extender repeats a weak signal and halves it.
- Then mesh, and only then talk about the plan. Upgrading a plan that your WiFi cannot deliver just buys speed you will not see.
A cable is not the "old" way. It is the quiet, boring way that keeps working at 9pm when the whole street is streaming.
FAQ
Why is my internet slower on WiFi than on a cable, when it is the same plan?
Because the plan is only the pipe coming into the house. After the router, WiFi shares one radio among every device in range, and only one device can transmit at a time. A cable gives each device its own private line. Same plan, two very different delivery methods.
Will a Cat6 cable make my WiFi faster?
No. Cables do not improve the radio. What a cable does is take devices off the radio, so the phones and tablets that stay on WiFi get a bigger share of it. The cable helps the whole house indirectly, not by making the WiFi signal stronger.
Can I just plug a cable into my phone?
Yes, with a USB-C to Ethernet adapter, and it is the cleanest way to run the comparison in this article on a device you already own. Most phones recognise the adapter immediately and switch off WiFi on their own; you may need to turn WiFi off manually to be sure the test used the cable.
My router says gigabit but the cable test tops out at 100 Mbps. Why?
Check which port you used and what the cable is. A damaged or badly crimped cable, or an old Cat5 cable with only two pairs wired, will negotiate down to 100 Mbps even on a gigabit router. Some routers also have one slower port reserved for the modem. Try a different port and a different cable before blaming the provider.