CakeQOS not limiting download

[eConnah]

Router Model Affected
Models: TUF-AX3000 V2

Firmware Version Affected
3004.388.8_2-gnuton1

Is this bug present in upstream Merlin releases too?
Unsure

Describe the bug
The bandwidth limiter for upload works perfectly well but for download it just doesn't work. It works using flex but I'm unsure why it doesn't with cake. I'm using pppoe on full fibre, 100/20 connection.

To Reproduce
Steps to reproduce the behavior:

1. Go to adaptive qos -> qos.
2. Click on cake.
3. Scroll down to manual bandwidth, enable set limits.
4. Run speedtest.
5. See download limit is not working.

Expected behavior
Download limit should work.

Screenshots

Fix from dave14305
tc filter add dev ppp0 parent ffff: protocol all prio 10 u32 match u32 0 0 flowid 1:1 action mirred egress redirect dev ifb4ppp0

Link: https://www.snbforums.com/threads/cakeqos-not-limiting-download.93504/

[dave14305]

CONFIG_NET_CLS_MATCHALL needs to be enabled for 4.19 kernel devices.