TDA4VM: After EST enables, the interval between the message becomes shorter

hello，

      I compare the same message through Plget before and after enable EST.

I am using TDA4VH and TDA4VM boards to verify  function. The SDK version I use is SDK8.5. The VH board uses the Native Driver mode ETH3 to send UDP packets, 80 bytes in length，use ETH0 to receive messages on the VM board for receiving.

When I do not set EST on VH

ifconfig eth1 down
ifconfig eth2 down
ifconfig eth3 down
ifconfig eth4 down
ethtool -L eth3 tx 3
ethtool --set-priv-flags eth3 p0-rx-ptype-rrobin off
ifconfig eth3 up
ifconfig eth3 192.168.5.100

the VM result 

But when I use the following command to enable EST

#!/bin/sh
ifconfig eth4 down
ifconfig eth1 down
ifconfig eth2 down
ifconfig eth3 down
ethtool -L eth3 tx 3
sleep 10

ethtool --set-priv-flags eth3 p0-rx-ptype-rrobin off
phc2sys -s clock_realtime -c eth3 -m -O 0 > /dev/null &
ip link set dev eth3 up

tc qdisc replace dev eth3 parent root handle 100 taprio \
num_tc 3 \
map 0 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 \
queues 1@0 1@1 1@2 \
base-time 0 \
sched-entry S 4 400000 \
sched-entry S 2 200000 \
sched-entry S 1 100000 \
flags 2


ifconfig eth3 192.168.5.100

the result is

I want to ask why the time interval of the message will change from 17us to 0.8us after enable EST？

best regards！