Manual:Network/Quality of Service
The Network ➤ QoS page configures the quality of service (QoS). With QoS you can prioritize network traffic that passes through the WAN port. You can limit the download and upload speeds. Network QoS is disabled by default.
Now that you're there, it's time to enable QoS, adjust its settings to fit your internet connection, and start adding your QoS rules. We'll start by setting up the connection.
After you enable QoS, you'll notice a slew of boxes that need filling out, so let's start from the top. First, to set our Uplink and Downlin speeds, which will determine how much real-world bandwidth your router will dedicate to each client. That means that first we need to get an idea of what your real-world bandwidth is. To do so, head to an internet speed test site (e.g. link Speedtest) and test your upload and download speeds (be sure you're not running any bandwidth hogs while you run the test, as it will provide inaccurate results).
Once you've got your speeds, you should enter roughly 85% of the up and down speeds in the corresponding Uplink and Downlink boxes.