Did you check https://openwrt.org/docs/guide-user/network/traffic-shaping/sqm ? If you are using PPPoE 1000/100 probably overhead should be 42, mpu 84. There is another thread in that forum related just for SQM configuration (you can even read that thread CAKE w/ Adaptive Bandwidth - #3159 by Lynx which is very interesting).
One more thing, HW offload should be disabled for best result. I accept lower bandwidth, lower ping and A score.
2 Likes