What Could Cause the Ethernet to not Connect to Internet, Yet Connect to Devices on Network
I don't have enough reputation yet to add comments above, so I'll put my questions here:


How does your MBP get the IP address for its ethernet interface?  DHCP?  Manually?
What is your default router set to (netstat -rn)?
Can you resolve, say, google.com (nslookup www.google.com)?
Can you ping any/all the servers mentioned in /etc/resolv.conf?


That should help to debug.

Thanks.