My SQM QoS Implementation (Bufferbloat fixing)

This post is a more in-depth detail that links to these previous posts:

After reading up on the OpenWrt implementation of QoS named SQM (Smart Queue Management) link OpenWrt documentation SQM I began my journey of fixing the bufferbloat on my network.

By default, OpenWrt does not have SQM installed.

You can install it with ease either in LuCI or via SSH

  1. Log into OpenWrt via your browser, usually a URL such as http://192.168.1.1 or http://10.0.0.1 but you should check this yourself.
  2. Via the menu go to: System > Software.
  3. Click Update lists… and wait for it to complete.
  4. Click Dismiss.
  5. Find luci-app-sqm in the results.
  6. Click Install… to the right of luci-app-sqm.
  7. Now click Install on the popup.
  8. Wait for it to install.
  9. Click Dismiss.
  10. Installation complete. Move to Configuring SQM section below.
  1. SSH into your OpenWrt router via your terminal or command prompt, you then need to connect to the router: (remember to replace the IP with your router IP) ssh [email protected]
  2. Once you are in, do the following commands:
  3. opkg update (now wait for it to complete)
  4. opkg install luci-app-sqm (now wait for it to complete)
  5. Installation complete. Move to Configuring SQM section below.

Configuring SQM via the browser is a dream, the UI is easy to use, and it works well.

So, the below is based on my internet connection speed as such take that into account when you configure your own.

My advertised connection speed is 950mbit.

Below are the screenshots of my working configuration that took my Bufferbloat score from a B grade to an A+:

OpenWrt SQM Link layer Adaptation

So, as you can see,850000 download speed is my sweet spot and is about 90% of my connection speed.

The documentation here: [OpenWrt Wiki] SQM (Smart Queue Management) has a great section at the bottom titled A Little More SQM Tuning which I found super helpful.

Keep tuning the numbers, example, I first tried:

But it did not improve my Bufferbloat issue.

Further, tuning down 10000 at a time until I got A+ was required.

Please feel free to comment on your experience or advice below. The only thing I am not too sure about would be the OpenWrt SQM Link layer Adaptation screenshot. I just used the values from the official OpenWrt docs

When in Doubt, it’s better to overestimate - Choose overhead 44 (mpu 96)

Now I experience zero lag spikes when playing Valorant online when there is high network usage. Along with Oculus 2 online play and Airlink/Virtual Desktop.

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