sudo nano /etc/network/interfaces
up sleep 5; ethtool -s eth0 autoneg off speed 100 duplex full
OR
In Debian (also Raspberry pi) this is the way to do it as per document
/usr/share/doc/ethtool/README.Debian
iface eth0 inet dhcp
link-speed 100
link-duplex full
ethernet-autoneg off
works like a charm
Reference: https://www.raspberrypi.org/forums/viewtopic.php?f=27&t=19067