What Could Cause the Ethernet to not Connect to Internet, Yet Connect to Devices on Network

ethernetNetworkssh

This has been my problem for about 6 months. On my 2011 MBP, if I connect a working ethernet cable to my ethernet port, it will either do nothing or my internet connection will die totally, even when I'm on a strong wifi network.

More intriguing (frustrating), when I jump on a network connected to a simple switch, I have no internet connection. I.E ping www.google.com gets request timeouts or unreachable hosts. But I can run ifconfig en0 ..., then ssh into another computer on the network, and from that ssh terminal I can connect to the internet no problem. My 'network', by the way, is just my laptop and a desktop connected to a network switch. This happens on multiple switches from different companies.

I've reset everything in Network Preferences, but no help. Has anyone seen this behavior? If so, what can I do to fix it?

Best Answer

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.

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