@gobs I've also come looking for the same answer! It doesn't make sense that you can only limit upload bandwidth - whilst this does have a direct affect on download bandwidth you should be able to limit a device for both upload and download!
It's a bit odd as in the web interface the description is as follows:
QoS
QoS (Quality of service) allows you to specify the priority of traffic and minimizes the impact of network congestion.
To set up QoS for the network
- Enable QoS.
- Choose the Line Type of your router’s internet connection.
- Enter the upload and download bandwidths provided by your ISP.
- (Optional) Enable IPTV QoS, then set the priority and reserved bandwidth of IPTV traffic.
- (Optional) Click Advanced and arrange the sliders to set the bandwidth percentage of each priority.
- Save the settings.
To set up QoS for a specific device
- In the QoS Rule List table, choose a priority section and click Add.
- In the QoS Rule window, click View Existing Devices and choose a device, then click OK to add it to the rule.
Now, traffic from the specified device will be granted the corresponding priority.
But once you've gone through the setup once you don't get the option to change anything (that I can find) in the web interface. If you look at QoS in the app however you can edit your upload/download speeds again - but you can't manage the list of QoS devices!