I don’t see you saying it explicitly, did you enable Mitigate Buffferbloat on the support.cgi hidden page?
The problem is that fq_codel and cake all rely on fixed bandwdth systems. People are trying to adapt them to dynamic links with PIE type algorithms, but are always going to have feedback problems, because you have to cause a queuing issue, to then know that you are saturated and back off the limits. And that limit is often 1-2 network hops downstream from you, not directly connected.