How to fix bufferbloat, step by step
Five steps from "my internet lags when someone downloads" to "it just works." Each step is the same whether you are on OpenWrt, pfSense, DD-WRT or a consumer router. As of 2026-11.
The five steps
- Test for it. Run the bufferbloat test or a manual before/after latency check while a large download is running. If idle is low and loaded is high, you have it.
- Find your real upstream. Do a clean upload test. The number is usually a little under the plan speed — use the measured value, it is what SQM paces to.
- Enable SQM with CAKE. The standard fix on every platform. OpenWrt: sqm-scripts + cake (NetSteer does this in one toggle). pfSense: CAKE queue. Consumer: QoS/CAKE if offered.
- Slow-path the real-time stuff. Games, calls, DNS go through CAKE's low-latency path so they keep priority.
- Confirm. Re-test. Full-load latency should drop under ~20 ms. If it is still high, lower the configured upstream a little and re-test.
Platform quick reference
| Platform | Fix | Effort |
|---|---|---|
| OpenWrt | NetSteer one-toggle (SQM + RPS + Fullcone) | Low — automated |
| pfSense / OPNsense | CAKE + SQM plugin | Medium |
| DD-WRT / FreshTomato | QoS/CAKE options | Medium |
| Consumer router | Enable QoS, or flash, or add a CAKE router | High |
If bufferbloat is not the whole story
On a soft router, single-core packet processing can still drop packets even after you fix latency — that is the RPS/IRQ problem. On P2P games, a symmetric NAT is what blocks you — see Fullcone NAT. NetSteer covers all three together.
FAQ
Can I fix bufferbloat without changing my router?
On a consumer router, only if it has a built-in CAKE/QoS option. Otherwise the cleanest fix is to flash it (OpenWrt/pfSense/DD-WRT) or add a small router with CAKE. The good news is you do not need new hardware for the common case — most routers that can be flashed support it.
Which fix is the most effective?
SQM with the CAKE queue discipline, paced to your measured upstream and with the slow path for real-time traffic, is the standard. On OpenWrt, NetSteer applies all of it in one toggle and shows you the measured A/B result.
Will fixing bufferbloat make my speed test faster?
No — and that is expected. CAKE trades a little peak throughput for much lower latency, so a speed test may read slightly lower while your gaming lag is far better. That trade is the whole point.