Why is my ping high when someone else is streaming or uploading?

Your router sits between a fast home network and a slower internet connection. When traffic arrives faster than the connection can send it, the router holds the extra packets in a queue, called a buffer. Bufferbloat.net defines bufferbloat as the undesirable latency that comes from a router or other network equipment buffering too much data (source).

A simple picture: the internet connection is a single checkout till, and the buffer is the line of shoppers. A stream or a backup is a shopper with a full trolley. If the line is long, your small purchase waits behind them, even though you only wanted to buy one item. Nothing is broken and no data is lost. Everything simply arrives late, and ping is exactly the measure of how late.

The queue was made deep on purpose. Bufferbloat.net explains that equipment makers fitted large buffers to avoid dropping packets, when the internet’s own protocols are designed to cope with a small amount of loss. The side effect is long delays whenever a link is full.

Streaming a film is mostly download, and it can fill the download side of your line. But upload is usually the first thing to saturate because home plans typically give you far less upload than download. A cloud photo backup, a video call from another room, a game upload or a large file sent by email can fill the upstream pipe quickly.

Calls and games are hit hardest because they send small packets many times a second and need each reply on time. A packet that waits in a full queue is late no matter how fast the line is. That is why a quiet-looking connection can have a huge ping problem the moment anyone starts something big, and why Teams video can freeze while your speed test is fine.

The giveaway is a gap between idle ping and ping under load. NetCheckPro measures both: it takes idle round trips first, then keeps timing round trips while it downloads and uploads, and reports the extra delay in the worse direction. Our how we measure page has the details.

1. Pause other devices if you can, then run the test above and note your idle latency on the latency test scale.
2. Read the Bufferbloat tile. It is the extra delay while the line was busy, graded in the table below. You can also run the dedicated bufferbloat test.
3. For a real-world check, open a command prompt and run ping -t 1.1.1.1 on Windows or ping 1.1.1.1 on macOS and Linux. Watch the times while someone starts a big upload or stream. Stop with Ctrl+C.
4. If the times are steady when the house is quiet and jump when it is busy, that is bufferbloat. For a quick ping reading from your browser, use the ping test.

Some very fast lines cannot be loaded enough by a browser to measure this, and in that case the result leaves bufferbloat out rather than guessing.

The grade is the extra delay measured while your connection is busy, not your ping itself. These are the bands NetCheckPro uses.

An A+ or A means a busy line should not bother you. Anything graded B or lower is worth fixing if you game or take calls at home while others are online. If you mostly play competitively, try the gaming ping test as well.

• Ping is high even when the house is quiet. That is not a queue problem. Look at Wi-Fi signal, the distance to the server, or your provider.
• Wi-Fi. Interference and weak signal cause delay that varies, and it is easy to mistake for bufferbloat. Test on Ethernet to tell them apart, or use the Wi-Fi stability test.
• The game server. Some games have a busy or distant server, which no home fix changes.
• Congestion at your provider. Usually worse at the same time each evening.

The fix is to move the queue out of the slow device and keep it short. Work through these in order.

1. Turn on smart queue management. SQM, with the fq_codel or CAKE algorithm, keeps queues short and stops one big flow from starving small ones. Bufferbloat.net names fq_codel, CAKE and sqm-scripts as the standard fixes (source). Look in your router’s settings for an option called SQM, Smart Queue or similar. OpenWrt firmware documents how to set it up.
2. Set the limit below your measured line speed. The shaper must be the slowest point so the queue forms in the router where it is controlled. OpenWrt’s guide suggests entering 90% of your tested download and upload speeds, then raising them until delay under load appears and backing off a little (source). Measure your speed with nothing else running, and test again after each change.
3. Use router QoS if SQM is missing. Prioritise your gaming console, work laptop or calls. It helps less than SQM, but it is better than nothing.
4. Use Ethernet for the device that matters. It removes Wi-Fi delay from the picture so you can see what the queue is doing.
5. Pause or schedule heavy uploads. Move cloud backups and photo syncs overnight. If uploads constantly fill the line, read the low upload speed fix guide too.
6. Replace the router if it cannot do the above. Choose one that advertises SQM or CAKE support and can shape your full line speed.

After each change, run the bufferbloat test again and compare the grade. If it does not improve, undo the change and try the next one.

• A lower ping when idle. Fixing bufferbloat does not change your ping when the line is quiet. It stops that ping rising when the line is busy.
• Full speed. A shaper set below your line speed gives up a slice of the top speed. That trade is the point: you lose a little peak speed and gain steady ping.
• A fix for Wi-Fi or provider problems. SQM only manages the queue at your router. It cannot repair a weak signal or an overloaded provider network.
• Every router can do it. Shaping a very fast line takes processing power, and some budget routers cannot keep up with it once enabled. Check the result with a test rather than assuming.
• A perfect score. Even a good grade only means the queue is under control. It says nothing about packet loss, which a browser test cannot measure.

Related reading: what is jitter, since a long queue is a common cause of uneven delay, and how to fix high jitter.