Browse to /etc/sysconfig/network-scripts/

Find your main NIC, commonly named eth0 , file usually named ifcfg-eth0

Add this line :

ETHTOOL_OPTS="autoneg off speed 10 duplex full"

NOTE : This works only on CentOS/Fedora/Red Hat.

NOTE : To check current NIC speed, run this command :

mii-tool eth0