Internet speed test: how to interpret it and what to do if it's slow

Running a speed test is easy. Interpreting it well is the hard part. The same router can give very different results throughout the day, depending on the time, the meter, and whether you're connected by WiFi or by cable. This guide explains how to measure your fibre properly, what the numbers mean (download, upload, ping, jitter) and what you can do if you're getting less than you pay for.

How to run a speed test correctly

Most of the tests people share over WhatsApp to complain about their fibre are done badly: over WiFi 5 metres from the router, with five devices downloading in parallel and a Bluetooth speaker interfering on the 2.4 GHz band. For a realistic measurement:

1. Connect the laptop to the router with an Ethernet cable. WiFi always adds variable losses — to know what your fibre really gives, measure over cable.
2. Close everything else: downloads, streaming, system updates, cloud backups. Just the browser where you'll run the test.
3. Pause syncing on other devices in the home: no one watching Netflix or a console updating while you measure.
4. Measure at different times. The real speed fluctuates: at 22:30 (streaming prime time) it usually drops because of congestion. Measure at 10:00, 16:00 and 22:30 to get an honest picture.
5. Run at least three tests in a row: discard the first one (server warming up) and take the average of the rest.

What the numbers mean: download, upload, ping, jitter

Any decent speed test gives you four numbers. Here's what each one means:

• Download — the speed at which you receive data from the internet. It's the figure you look at most: how long Netflix takes to load, downloading a game, opening a heavy website. Measured in Mbps (megabits per second).
• Upload — the speed at which you send data to the internet. It matters for video calls (the image you send), uploading files to the cloud, going live on streaming. On symmetrical fibre (FTTH) it should be equal or very similar to download. On cable or ADSL the upload is much lower than the download.
• Ping or latency — the time a packet takes to go and come back, measured in milliseconds (ms). The lower, the better. Below 30 ms is excellent for video calls and online gaming; between 30 and 80 ms is good for normal use; above 100 ms you notice sluggishness in interactions.
• Jitter — the variation in latency between consecutive packets. If your ping fluctuates a lot (sometimes 20 ms, sometimes 90 ms), video calls break up even if the average looks good. Ideally under 10 ms.

Ookla Speedtest vs. fast.com vs. operator meters

The three types of meter don't measure exactly the same thing:

• Speedtest.net (Ookla) — the industry standard. It measures against a nearby server on its network, but lets you choose the server manually. It gives download, upload, ping and jitter. The most useful for a general measurement.
• fast.com (Netflix) — measures specifically how much your fibre gives against Netflix's servers. Useful for finding out why your streaming is bad. It doesn't show upload or ping on the main screen (you have to click "Show more info").
• Operator meter (Movistar, Digi, Vodafone…) — connects to a server inside the operator's own network. Result: figures typically more optimistic than the "real" speed test out to the rest of the internet, because they avoid the bottleneck of the exit to the outside. Useful only if you want to rule out that the bottleneck is outside your operator's network.

Honest recommendation: use Ookla first and, if the numbers don't match what you notice in real use, cross-check with fast.com.

Speed tests by operator (Movistar, Digi, Vodafone, Orange)

Each of the big operators has its own internal meter. They're useful for complaining over chat (the operator accepts its own test without arguing) and for ruling out issues inside its network:

• Movistar — Speed test available in its customer area and in the Mi Movistar app.
• Digi / DigiMobil — Test on its website (test.digimobil.es). Much searched by the Romanian community in Spain as "test velocidad digi".
• Vodafone — Test available in Mi Vodafone (app and web).
• Orange / MasOrange — Test on the Orange support page.
• R (Galicia) — R speedometer (much searched by Galician users) on the R / Mundo-R website.

Trick: run the operator's test first, then an Ookla one and a fast.com one. If all three come out fine, your fibre is OK. If only the operator's comes out fine, the problem is outside its network (peering, exit congestion to Netflix, etc.) — the operator won't fix it easily.

How much speed your fibre should really give you

On FTTH fibre (the norm today in areas with coverage), over a cable directly to the router and with nothing else using the network, you should see at least 80–90% of the contracted speed. That is:

• 300 Mbps contracted → see between 270 and 300 Mbps over cable.
• 600 Mbps contracted → see between 540 and 600 Mbps over cable.
• 1 Gbps contracted → see between 850 and 950 Mbps over cable (the practical ceiling of Gigabit Ethernet is ~940 Mbps).

Over WiFi you'll always see less: with a modern WiFi 6 router and a compatible laptop, right next to the router, it's around 600 Mbps real — that's already very good. If your laptop is old (WiFi 5 or earlier) you'll see at most 300-400 Mbps over WiFi even if your fibre is Gigabit. It's not a fibre problem: it's the ceiling of the laptop's own WiFi.

What to do if your fibre gives less than you pay for

If you've run the tests properly (over cable, at different times, several samples) and you see that the real speed is clearly below what you contracted:

1. Restart the router by turning it off for 30 seconds and back on. Sometimes it gets misconfigured after an outage.
2. Call your operator's technical support and share the result of its own test. They usually open a ticket and send a technician within 24–72 h if they confirm the line isn't performing.
3. Ask for a new router. If your router is more than 3-4 years old, it's limiting the speed even over cable. Most operators provide a new one free if you've been with them 2+ years and you ask.
4. If that doesn't fix it, complain in writing from the customer area. Give the operator 30 days. If it still doesn't resolve, escalate to the Telecommunications User Service Office.
5. Switch operators if nothing changes. Real speeds vary between Movistar, Vodafone, Orange, MasMovil, Simyo, Digi and others — especially in areas with several fibre networks. If your current plan has no commitment, switching is free. If you have commitment left, a real speed clearly below the guaranteed minimum is grounds to cancel without penalty.