What Is Packet Loss? (And How to Test for It)

Packet loss is a connectivity issue where “packets” of data are lost before reaching their destination. Test for packet loss locally and over the Internet with a simple command line tool to isolate the problem. Make changes to your network setup or contact your ISP to resolve the issue.

Packet loss can ruin your network connection. Fortunately, testing for it is relatively simple on both a local connection and over the Internet. Here’s what you need to know before you complain to your ISP.

What is a package?

In network terms, a packet is a small piece of a larger message that has been broken up for efficient delivery. Packets are used because computer networks are “packet switching” networks. This means that packets can travel independently of each other and be processed over the same connections in any order, before being reassembled once they reach their destination.

It is fundamental to the Internet’s infrastructure, where a large number of devices make up the larger network, all communicating and sending data at the same time. Without packets, data would be sent as one long stream, which becomes impractical once more than two devices are introduced.

All data transmitted over local and global computer networks is broken up into packets of approximately 1500 bytes. Internet Protocol packets consist of a header (which includes information such as source and destination IP addresses, packet types, and the packet number) and a payload (the data you transmit).

What is packet loss?

Packet loss is what happens when one of these packets fails to reach its destination. This results in incomplete data on the receiving end, requiring data to be sent again to successfully process the request.

Random packet loss can occur as part of “normal” network performance. This is not desirable, and can lead to a slow network, interrupted streams, lag, and things not working the way they’re supposed to.

Packet loss is more evident in certain online activities, especially gaming, streaming, and real-time voice and video communications. You may notice jerky movement in games, network timeouts, or random disconnection. Packet loss during streaming or voice and video calls can cause freeze frames, stuttering, robotic audio or macroblocking (heavy pixelation caused by compression).

Although packet loss is bad, you usually don’t need to worry about it unless it’s a constant problem.

What causes packet loss?

Most of the time, packet loss is caused by factors beyond your control. This may be due to problems with services you use, telecommunications infrastructure or internet service provider outages. Packet loss can affect both local networks and the wider Internet. If you are experiencing problems on your local network, the problem is caused by a problem on your end.

This can be due to factors such as:

• Problems with network hardware.
• Interference on wireless or wired networks.
• Software problems with computers and other devices.
• High loads on network hardware (such as routers, switches or wireless repeaters).

How to test for packet loss

You can test for packet loss over a local network or the Internet. This can help you decide whether the problem is on your end or not, and whether you should involve your ISP or telecom provider.

Test for local network packet loss

An easy way to test for packet loss is to use the ping console command. On Windows, you can do this by starting PowerShell (use the Search function in the Start menu to find it).

First find out the address of your router using the ipconfig /all command and look for the IP address listed next to the “Default Gateway” entry. In most cases this will be 192.168.0.1 or 10.0.0.1.

Now run ping <address> -t in PowerShell, where <address> is the IP address of your router. The ping command will run indefinitely, each time a single packet of data is sent. Let it run for a while, then press Ctrl+C to cancel the command.

Any packet loss experienced will be listed. Ideally, you want to see “0% loss” reported for this test. This means that the connection between your computer and your router does not drop packets.

To do this on a Mac or Linux computer, use the Terminal application. Start the netstat -nr|grep default command to see your router IP address at the top of the page. Now run ping <address> replace <address> with the router IP address.

The command will run indefinitely, sending and receiving a single packet each time. Let it run and then press Control + C to cancel the command. You will see any packet loss listed. If you see “0% loss”, your local connection is not dropping packets.

Test for Internet connection packet loss

You can use a similar method to test your Internet connection for packet loss, except instead of your local router IP address you can use a website URL like howtogeek.com or google.com.

Internet speed test sites such as speedtest.net or packetlosstest.com will also notify you of any dropped packets. You are more likely to encounter packet loss over the Internet, as there may be many hops between your computer and a remote server, meaning more potential points of failure.

RELATED: How do internet speed tests work? (and how accurate are they?)

How to fix packet loss

If you suspect the problem is on your end, eliminate as many causes as possible before changing too many variables. Restart your computer and apply any outstanding software updates. Do the same for network hardware, especially if it’s been a while since you’ve used power cycling.

If your network equipment is under heavy load, test at a time when loads are lighter. Rather than doing it during the day when everyone is trying to use the internet, do it late at night when everything is down.

Repair packet loss on a local network

Wi-Fi is a common cause of lost packets on a local network. The obvious solution is to use a wired network, although this is not always practical. You can at least test to see if the problem persists on a wired network to isolate Wi-Fi as the cause of your problems. Ideally, this would involve moving a laptop near your router and connecting it via Ethernet and then running the above tests again.

If it turns out that Wi-Fi is to blame, you can take some steps to mitigate problems by removing sources of network interference and tuning your channel accordingly. You may want to try switching between the 2.4Ghz and 5Ghz frequencies to see if that helps.

If you are already using a wired connection, check and replace any cables that may be damaged. Powerline networks can also be affected by interference, resulting in packet loss. Try turning off major appliances and testing again to isolate the source.

If your router is old and easily overloaded, replacing it with a modern mesh routing system or high-performance Wi-Fi 6E router may be the answer.

Fix packet loss over the Internet

Hardware can also be blamed for problems that go beyond your local network. Always restart your computer and your network hardware and then test over a wired connection if you suspect this is the case. If you have a separate modem (or a combined router-modem), consider that this could also be to blame. If you can test with other hardware, do so.

If you’re confident that the problem is your connection, it’s time to go to your Internet service provider or telecommunications company to fix the problem. Tell them exactly what the problem is, what you’ve learned, and what kind of symptoms you’re having (such as streaming issues, lag issues when playing games, slow web browsing, etc.).

Make a note of when you encounter these problems, whether it’s all the time, during periods of heavy use, or sporadically. Be aware that some service providers may bill you for a call if they find there is nothing wrong with your connection. Borrowing a modem and router from a friend to exclude your own equipment can save you money!

Also check for excessive lag

Latency can be one of the biggest sources of connection struggles, a problem that plagues even relatively “fast” connections like satellite Internet. This is one of the many reasons why your internet connection may seem slow.