My solution if someone need it :
add a service
[Unit]
Description=/etc/rc.local Compatibility
ConditionPathExists=/etc/rc.local
[Service]
Type=forking
ExecStart=/etc/rc.local start
TimeoutSec=0
StandardOutput=tty
RemainAfterExit=yes
SysVStartPriority=99
[Install]
WantedBy=multi-user.target
And add the rc.local file
#! /bin/sh
ethtool -s eth0 speed 100 duplex full autoneg off
exit 0