sudo ip link set eth0 mtu 1500
!
sudo ifconfig
!

Enable MTU Path Discovery:

sudo vi /etc/sysctl.conf
!
# Path Maximum Transfer Unit discovery–disable this and the MTU settings are derived
# from the MTUs of all the hops along the# path to the host you are connecting to,
# including the host itself; 1 enables, 0 disables
net.ipv4.ip_no_pmtu_disc = 1

Allow MTU Path Discovery through the firewall :

sudo iptables -I FORWARD 7 -i eth0 -p tcp –tcp-flags SYN,RST SYN -j TCPMSS –clamp-mss-to-pmtu
sudo iptables -I OUTPUT 7 -i eth0 -p tcp –tcp-flags SYN,RST SYN -j TCPMSS –clamp-mss-to-pmtu