Why Is My Internet Slower Than Advertised?

“Up to” is a ceiling, not a promise

ISP plans are marketed as “up to” a number for a reason: that figure is the best case, measured under ideal conditions the plan rarely delivers in practice — a wired connection, no other traffic on the line, and a test server close to the ISP’s own network. Every layer between that ideal case and your actual device — Wi-Fi, your router, shared neighborhood infrastructure, the test server itself — can take a bite out of the number before it reaches you.

The most common causes

• Wi-Fi, not your line. Wi-Fi shares airtime with every other device on the same channel — neighbors’ networks included — and older 802.11n/ac hardware or a 2.4 GHz connection caps out well below gigabit regardless of your plan. Test over Ethernet to isolate whether the bottleneck is your line or your Wi-Fi.
• Network congestion at peak hours. Cable and some fiber networks share bandwidth across a neighborhood segment; results commonly drop in the evening when everyone nearby is streaming at once, and recover overnight.
• Router or modem hardware limits. Older routers have wired and wireless throughput ceilings well below what modern fiber and cable plans deliver — a five-year-old router is a common, invisible bottleneck on a recently upgraded plan.
• Distance to the test server. A test that routes your traffic across the country will always measure lower than your real line speed. This is exactly why netgauge runs on Cloudflare’s 300+ edge locations instead of a single origin server — see the methodology for how that works.
• A VPN or active download elsewhere on the network. A VPN adds a hop and encryption overhead that directly caps throughput; a device mid-download or mid-backup on the same network eats into whatever bandwidth your test can measure.
• Server-side throttling on the test itself. Some free speed tests cap concurrent connections or bytes served, understating a genuinely fast line. netgauge runs 6 parallel streams and scales request size up adaptively specifically to avoid this failure mode — see the full methodology.

A fast number that still feels slow

If your download number looks fine but calls stutter or games lag, the number itself isn’t the problem — bufferbloat usually is. A high Mbps figure and a bad bufferbloat grade can coexist on the exact same connection.

Narrow it down

Run a test wired and over Wi-Fi, at a quiet hour and a busy one, and compare against the thresholds your actual use case needs rather than your plan’s advertised ceiling.