"My internet is slow" is the helpdesk's vaguest ticket. Five minutes with a speed test turns it into actionable diagnostics.
1. The right speed test
The most reliable browser-based tests:
- Speedtest.net — long-running, large server pool
- Fast.com — Netflix's, measures real video streaming
- Cloudflare Speed Test — includes latency variation under load
Run two of them. If both agree, you have a clean reading.
2. Understand the numbers
A speed test gives you three things:
- Download speed (Mbps) — how fast websites load and videos stream
- Upload speed (Mbps) — how fast you send files, video calls, screen-sharing
- Latency / ping (ms) — round-trip time to the server
For a busy office:
- 25 Mbps down per concurrent user (audio calls don't count much)
- 5 Mbps up per concurrent user
- Latency below 50ms
If you're seeing 100 Mbps down on a quiet test but a meeting is breaking up, the problem is upload or latency, not download.
3. Wired vs. Wi-Fi
Always test both. Run the speed test on:
- Wired Ethernet (if available)
- Wi-Fi on the same laptop
Wi-Fi is typically half of wired in optimal conditions. If wired is 200/50 but Wi-Fi is 30/10, you have a Wi-Fi problem (see [slow Wi-Fi](/kb/slow-wifi)).
4. Compare against the office's nominal speed
Find out what your office is provisioned for (ask IT, or it's usually in the contract). If you're paying for a gigabit link and seeing 100 Mbps, something between you and the modem is bottlenecking.
Common bottlenecks:
- Your laptop's Ethernet is 100 Mbps not gigabit
- The switch port is configured for 100 Mbps
- The patch cable is Cat5 not Cat5e
- Wi-Fi can't physically deliver gigabit even when nominal
5. Time of day
Office Wi-Fi gets crushed at peak: 09:30 (everyone arrives), 10:00 (stand-ups start), 14:00 (post-lunch backup runs). Speed test at three different times — if morning is fast and afternoon is slow, you have congestion, not a fault.
6. Test the underlying internet (not just Wi-Fi)
If possible, test on:
- A phone on cellular (sanity check that you have a cell signal)
- A phone on the office Wi-Fi
- Your laptop on the office Wi-Fi
- Your laptop on Ethernet
Comparing helps localize the problem to a layer.
7. Reading latency under load
For meetings, latency consistency matters more than peak speed. The Cloudflare Speed Test shows latency during the test:
- Idle latency: under 30ms is excellent
- Loaded latency: ideally less than 100ms above idle
- Jitter: under 20ms
If loaded latency spikes to 500ms+, your meetings will choke even though "download speed" looks fine.
What to include in a ticket
If you're raising a slow-network ticket, attach:
- Screenshot of speed test (with the server name and timestamp visible)
- Whether you're on Wi-Fi or wired
- Time of day
- Whether you're VPN'd in
That single screenshot saves the network admin an hour.