DSCP, UDP/TCP and iperf question

RouterOS Beginner Basics
1

I’ve been doing some tests with iperf sending udp and tcp traffic from pc A to pc B using a MT RB951 and trying to change the udp and tcp DSCP using mangle rules. By checking the DSCP field in pc B with wireshark, the ToS field shows a 0x00, nothing changed.

 0   chain=prerouting action=mark-connection new-connection-mark=udp 
     passthrough=yes protocol=udptraffic src-address=192.168.88.0/24 

 1   chain=prerouting action=mark-packet new-packet-mark=udpqos passthrough=yes 
     connection-mark=udp

 2   chain=prerouting action=change-dscp new-dscp=63 passthrough=yes 
     packet-mark=udpqos

I used these rules for HTTP and adding dst port 80 and it worked. Am I missing something?