You can try restarting network services
sudo /etc/init.d/networking restart or try bringing the interface up and down again,
sudo ifdown eth0 && sudo ifup eth0.
Additionally, you can try having him do
ping -c 3 66.102.7.147 and
ping -c 3 www.google.com. If the first one works (by IP address) then he's connected to the net. If the second one doesn't work, then you need to add a nameserver to /etc/resolv.conf. You can get a nameserver from his ISP...