How to change ECN bytes in IP Header

RouterOS Beginner Basics
1

Dears, we use a provider with a link equipment that uses the ECN bit, to say yo link equipment that the equipment not buffer data sended.

I try with mangle set priority and then change TOS, but i see that is impossible to change the two bits of ECN IP header.

In the next documentation I read that ROS can change all bits.https://www.mikrotik.com/testdocs/ros/2.9/ip/flow.php How can do it? Is it posssible to do?

I’m using ROS 6.19

Thanks a lot,