If the problem you are trying to solve is slower upload and download speeds when using a VPN the problem won't be solved by adjusting QOS.
The problem is the fact that most SOHO routers don't have powerful enough processors and enough memory to quickly and efficiently handle VPNs.
You can easily test that this is the root of your problem.
Start by connecting to your router using an Ethernet cable. To eliminate other uncontrolled variable, turn of the radios, disable QOS and port forwarding if it isn't needed.
Then run several speed tests with the VPN running on your router and come up with an average speed.
Then disable the VPN on your router and run speed tests to the same speedtest server as used previously and compute an average.
Then to demonstrate the impact of the lack of processing power run the VPN on your computer and connect to the same speedtest server.
If the lack of processing power explains your problem and you want maximum throughput while running a VPN on your router you will have to find a hardware solution with more processing power and not worry about QOS.
If the lack of processing power explains your problem and you want maximum throughput while running a VPN on your router you will have to find a hardware solution with more processing power and not worry about QOS.
This is something where the soon-to-be-released RT-AC56U (and its future big brother RT-AC68U) will be a good improvement, thanks to their 800 MHz dual-core CPUs.
Thanks I can't wait for the AC-68U. However I could benefit from QOS now.
The CPU certainly is a limiter but as you know, when you run your own VPN, your upload and download speeds reverse. I only have 5 mbps up. I'm constantly using ~3 in the background.