Your video call freezes mid-sentence. Your game character teleports across the map. A web page loads halfway and stalls. Your speed test says everything is fine, so what is going on? Often the answer is packet loss: small pieces of your data are being lost on the way, and your apps have to wait for them to be sent again.

Data travels across the internet in small units called packets. Normally, every packet arrives. When some do not, the receiving end has to ask for them again, which adds delay, stutters, and freezes. A little packet loss is invisible. A lot of it makes even a fast connection feel broken.

What packet loss actually is

Imagine sending a letter in ten envelopes and only eight arriving. That is packet loss. It is measured as a percentage: if you send 100 packets and 2 never arrive, that is 2 percent loss. Under 1 percent is generally fine and unnoticeable. Between 1 and 2.5 percent, you may start to notice stutters in calls and games. Above 2.5 percent, video calls freeze and games become hard to play. Above 5 percent, even browsing and streaming suffer. The key point is that packet loss is different from slow speed: a connection can show 300 Mbps on a speed test and still lose packets, because the test measures capacity while packet loss measures reliability.

How to test for packet loss

Start with a dedicated test. A packet loss test sends a stream of packets to a server and counts how many come back, giving you a percentage over a set period. You can run a free packet loss test to check your connection right now. Run the test for at least 30 to 60 seconds, since a five-second test can miss intermittent loss, and run it more than once at different times of day. For a deeper check, you can use your computer's built-in tools: on Windows, the ping command with a high packet count shows loss over time, and on Mac and Linux the same command works in the terminal. If the loss appears only at certain times, note the pattern, since evening-only loss usually points to congestion.

Reading your results

Zero percent loss over a minute of testing means your connection is healthy right now. Occasional loss of under 1 percent is normal on Wi-Fi and on busy networks, and it rarely causes visible problems. Steady loss above 2 percent deserves attention, and loss above 5 percent is a real fault that will affect calls and games. Pay attention to where the loss happens, too. If a test to a nearby server shows no loss but a test to a distant one does, the problem is somewhere along the route, not in your home. If every test shows loss, the fault is more likely in your own network or line.

Common causes of packet loss

The most common cause at home is Wi-Fi: weak signals, interference from neighbours, and congestion on the 2.4 GHz band all drop packets. Old or overheating routers drop packets too, especially when many devices are connected. Damaged or loose Ethernet cables are a quiet culprit, as is a failing network port. Beyond your home, congestion at your provider's network during peak hours causes loss, and a faulty line or a damaged cable outside can do the same. In games, loss can also come from the game server itself being overloaded, which is why testing against more than one destination matters.

Fixes that work, in order

Work from the cheapest fix upward. First, restart your modem and router, since a reboot clears memory and temporary faults. Second, switch from Wi-Fi to Ethernet for the affected device, which removes wireless interference entirely. If you must use Wi-Fi, move closer to the router, switch to the 5 GHz band, and change the Wi-Fi channel to one your neighbours are not using. Third, replace the Ethernet cable and try a different router port, since both fail more often than people expect. Fourth, update your router's firmware. If loss persists on a wired connection with a new cable, the fault is likely on the line: record your test results over several days and send them to your provider, since documented evidence gets a faster response than a vague complaint.

Key Takeaways

- Packet loss is lost data, not slow speed: even fast connections can suffer from it.

- Under 1 percent is fine; above 2.5 percent causes visible problems in calls and games.

- Test for at least 30 to 60 seconds, more than once, and note when the loss happens.

- Ethernet, a router restart, and a new cable fix most home packet loss.

Frequently Asked Questions

Q: What causes packet loss on Wi-Fi? A: Weak signal, interference from other networks, too many devices, and congestion on the 2.4 GHz band are the usual causes. Ethernet removes most of them.

Q: Can packet loss affect streaming video? A: Yes, though streaming hides it well by buffering ahead. Severe loss causes buffering, quality drops, and stalls, especially on live streams.

Q: My speed test is fine but my game lags. Is it packet loss? A: Possibly. Speed tests measure capacity, not reliability. Run a packet loss test and check your ping and jitter: high loss or jitter explains lag that speed alone cannot.

Packet loss is invisible on a speed test and miserable in real use. Test for it properly, fix the home causes first, and take documented results to your provider if the problem survives everything you try.