LAN Speed Test
Measure device-to-device speed on your own network — cable vs Wi-Fi. It needs a local agent to run, so here's how it works and how to test today.
A local test needs a local helper
Measuring speed inside your network — between your laptop and a NAS, or cable versus Wi-Fi — is something a web page can't do alone. Browsers can only reach internet servers, not your other devices. The full test will run through a small local agent; here's the interface it will drive.
What a LAN speed test measures
A LAN (Local Area Network) speed test measures how fast two devices on your own network can move data between each other — your laptop and a network drive, a desktop and a media server, or simply one room versus another. Unlike an internet speed test, it never touches your ISP, so it isolates the part of the chain you actually control: your cabling, switch, router and wireless adapters.
Because a browser can only reach servers out on the internet — never the devices sitting next to you — a real LAN test runs through a small local agent installed on the machines being tested. That agent opens a direct connection between them and pushes data to find the true throughput. It's on our roadmap; the panel above previews how it will look.
Cable vs Wi-Fi: how to read the gap
The classic use of a LAN test is settling the cable-versus-Wi-Fi question. Wired Ethernet is faster, steadier and almost loss-free; Wi-Fi trades some of that away for convenience. If a wired transfer flies but Wi-Fi crawls, the bottleneck is your wireless link — distance, interference or an old standard — not your internet plan.
| Metric | Wired (Ethernet) | Wi-Fi |
|---|---|---|
| Typical speed | Up to 1–10 Gbps, full and steady | A fraction of the rated number, varies by room |
| Latency | Lowest, rock-steady | Higher, jittery under load |
| Packet loss | Near zero | Rises with distance and interference |
| Best for | Gaming, big transfers, NAS, calls | Phones, tablets, roaming around the house |
Frequently asked questions
Why can't I run a LAN speed test in the browser?
A LAN test measures the speed between two devices on your own network — for example your laptop and a NAS. A web page can only talk to servers on the internet, not to other devices on your local network, and it can't open the raw connections a true throughput test needs. That work has to run as a local app or agent on both ends.
What's the difference between a LAN test and an internet speed test?
An internet speed test measures the link from your device out to a remote server, so it includes your ISP. A LAN test stays inside your home or office and measures device-to-device speed, which tells you whether your cabling, switch and adapters can keep up — independent of your internet plan.
How can I test my LAN speed today?
Use a local tool such as iperf3 between two computers, or simply copy a large file between two devices and watch the transfer rate. For Wi-Fi versus cable, run the same copy once over Ethernet and once over Wi-Fi and compare.
My internet is 1 Gbps but file transfers are slow — why?
The weakest link sets the speed. An old Cat5 cable, a 100 Mbps switch port, a slow hard drive or a distant Wi-Fi connection can all throttle a local transfer well below your internet speed. A LAN test isolates which one.
Want answers right now?
While the local LAN test is in development, the Doctor can already test your connection end to end and tell you whether Wi-Fi, your router or your ISP is holding you back — in plain English.