Your speed test says 500 Mbps, yet the game rubber-bands the moment someone starts a download. That's bufferbloat: latency that only appears while the line is busy. Our network test measures your ping at idle, then again while saturating the connection in both directions, and grades the difference A–F.
The bufferbloat run is part of the full network test — one click measures ping, download, upload, and then latency under load with your grade.
Run the network test →The grade is the median ping increase while the link is saturated — measured separately for downloading and uploading; the worse direction sets your grade.
A speed test measures how much data moves when nothing else matters. Bufferbloat is the opposite question: what happens to everything else while data is moving? Oversized buffers in modems and routers hoard packets when the line saturates — throughput looks great, but every small, urgent packet (a mouse click in a game, a syllable in a call) waits behind megabytes of bulk transfer. That's why your connection can test "fast" and still feel terrible.
The fix is rarely more speed. It's a router that keeps its queues short: look for SQM, fq_codel, CAKE, or a QoS mode where you enter your line's real speed. Properly configured, most connections jump to an A grade while giving up only a few percent of raw throughput.
Latency caused by oversized buffers in your router or modem. Under load, packets queue in those buffers instead of being dropped, and everything behind them waits. Speed stays high; responsiveness collapses.
A or B — under about +60 ms, most games and calls absorb it. C is noticeable; D or F means one download can break the connection for everyone on it.
Enable Smart Queue Management on your router (SQM, fq_codel, CAKE, or a gaming/QoS mode with your line's real speed set). It typically turns an F into an A for a few percent of throughput.