@kc0jaz,

I believe that lowering your QoS to below what your ISP gives would limit the speed of your enitre network.

Essentially, you are telling your network what you will reliably be able to receive, and your network is then using that information to provide a limit for each device so that other devices can communicate simultaneously; or prioritized in the case of High-Priority devices. QoS is a complex system, so there is no definitive answer. However, a High-Priority Device should try and make use of the most bandwidth available to it, sometimes at the cost of another device's network performance.The effects of QoS aref far less likely to be seen at higher throughputs since your device will not likely be using the entire bandwidth.

Is there a specific reason that you are looking for this feature?

If you are trying to limit your data usage, you may look at other options, such as adding switches that provide bandwidth control to your network. You should also consider checking with your ISP and their equipment to see if there is an option to limit the throughput at the source.