QoS not working properly because of docsis 3.1?

These are the settings I have them on currently, and yes I have share excess enabled. I've tried giving a very large percent of bandwidth to a certain device before testing it, and also have tested it by only having 1 device connected before testing, but it still makes no difference. No matter how my settings are, if I have QoS enabled I always get a download speed about 40-50mbps lower than what I have it set to, but when I have OoS disabled it gives me my normal maximun speed that I should get from my ISP. I've also tried swithching it to "always" have anti--bufferbloat on instead of "when high priority traffic detected", but that hasn't made any difference either. I've tried doing factory resets multiple times but it's never fixed it whatsoever.