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