Congestion Control Auto-Setup Keeps Messing Up

The servers it uses are hardcoded into the router and they are old ones and so don't run very well if at all. I'd suggest testing with downloads while following: https://support.netduma.com/frequently-asked-questions/legacyfaqs/test-your-ping/ start with a high value e.g 95%, test, decrease 10%, test, decrease 10% etc, until you get to a value that is pretty good, then try 5% either side of that value to see if it can be improved. Important to note that Download/Upload on CC don't have to be the same value & you may have a better experience with differing values. This is more of a real world test.