DOCSIS 3.0 How should SQM setting be for

This is how I use it now;

Link layer: Ethernet with overhead select for e.g VDSL2

Per Packet Overhead (bytes): 18

Advanced Linklayer Options: Turn off

Queueing discipline: cake

Queue setup script: piece_of_cake_qos

Advanced Configuration: Turn off

Donot change any parameter?
docsis supports various media encodings, you really can not guess at its current speeds.

I made changes in the link layer section, my internet speed is 100/5 MBPS

Is it MB or Mb?

Megabit Per Second

See here:
https://openwrt.org/docs/guide-user/network/traffic-shaping/sqm

  • DOCSIS Cable - choose Ethernet, and for rates < 760 Mbps set overhead 22 (mpu 64), for rates >= 760 Mbps set overhead 42 (mpu 84).

to set the mpu you need to turn on the "Advanced Linklayer Options"