Idle ping is 20 ms. Ping during a download is 500 ms. That's bufferbloat.
Bufferbloat is when your router (or your ISP's gateway) builds up huge packet queues under load, causing latency to balloon from 20 ms idle to 500+ ms when you're downloading. Your speed test still shows high speed, but anything interactive — video calls, gaming, even loading a webpage in another tab — falls apart while the download is running.
Bufferbloat is one of the most common modern internet problems and one of the most under-recognized. The fix is usually a router setting (SQM / fq_codel) or replacing the modem.
Bufferbloat is invisible to ordinary speed tests because they only measure idle latency or speed alone — never both at once. But for anyone in a household where one person streams while another video calls, bufferbloat is the silent killer of call quality.
Bufferbloat is when network queues grow too large under load, causing huge latency spikes (20 ms → 500 ms) even though bandwidth is fine. It breaks anything interactive while a download is running.
Most cheap routers do. ISP-provided modems are especially bad. A router with SQM/fq_codel (often labeled QoS) fixes it. Or replacing the modem with an OpenWrt-based one.
No. Bufferbloat connections are usually fast in raw speed but feel slow under load. A 200 Mbps connection with bufferbloat can have 500 ms ping during a download — gaming and calls feel terrible.
Most speed tests measure speed and idle ping separately. Bufferbloat only appears when you measure latency DURING a download — which Signalyzr's bufferbloat test does.
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