The usual bottlenecks on fiber
With slower plans, the internet connection is usually the limit. With fiber, it is often something in your home. Work through these before deciding the line is slow:
| Part | Common limit | What to check |
|---|---|---|
| Network port | 1 Gbps on most laptops and desktops | For multi-gig plans you need a 2.5, 5 or 10 Gbps port or adapter |
| Ethernet cable | Old or damaged cables may only link at 100 Mbps | Use Cat 5e or better for 1 Gbps, Cat 6 or better for longer multi-gig runs |
| Router | Router ports or processor may top out below plan speed | Check the router’s specifications and the port your computer is plugged into |
| WiFi | Often a few hundred Mbps in practice, less through walls | Test on a cable first; then test WiFi close to the router |
| Device and browser | Older processors and busy browsers can’t keep up | Close other tabs; use an up-to-date browser on a recent computer |
Testing multi-gig plans
Plans of 2 Gbps and above need every part of the chain to be multi-gig: the provider’s equipment, the router port, the cable and your computer’s network adapter. Even then, a browser-based test has limits. It is running inside a web page alongside everything else your browser does, and at very high speeds the processor can become the bottleneck.
This test ramps up to large transfers (up to 250 MB per download request) so that fast connections have time to reach full speed. Treat a multi-gig result as a lower bound: the line is at least this fast, and it may be faster than the browser can measure.
What fiber should look like
- Upload close to download on symmetric plans. If upload is much lower than the plan says, check the plan details first; not all fiber plans are symmetric.
- Low, steady ping. Fiber usually has lower latency and jitter than cable or DSL to nearby servers.
- Small rise in ping under load. If ping jumps when the test is downloading, your router may need smart queue settings. Try the bufferbloat test.