ethernet internet connection stopped working

Question

I had been using mac wireless to share internet access with my raspberry pi2 via a usb modem's ethernet connection:

wifi --> mac (wireless!) mac --> insignia usb modem (direct usb connection to mac) insignia usb modem --> raspberry pi ethernet port (via ethernet cable)

I had no problems with this for a couple of weeks but all of a sudden it stopped working. I had been editing my config.txt file to get the pi2 to work with a dell monitor and when the monitor starting working at my desired resolution I noticed the internet connection on the pi stopped working. (not necessarily related!)

Can anyone help me troubleshoot this? or point me to a comprehensive guide to checking the ethernet connection?

I never checked before but now the ethernet connection on the pi2 has one green and one yellow light.

Answer 1

I assume that the internet is not down (assuming you used the same network to post this question). also, that you have rebooted both the Mac and Pi? Have you tried reverting your change to config.txt and retrying (this will confirm wheter the network issue was just coincidence).

To start with the obvious:

• Can you ping the mac from your Pi?
• Can you ping your router?
• Can you ping google.com?

This will let us know where in the chain the connection is broken.

To rule out is the PI's Ethernet port and software. Connect the Pi directly to your router and try opening a page in your browser. If this works you know the problem is on the Mac side. (If you made changes to the networking configuration on the Pi you may need to modify them to work in non-shared Ethernet mode).

If that still does not work swap the cable out and try again. This will eliminate the cable as the source of the problem.

If you are still having problems, can you edit your question and include the output of ifconfig and the contents of /etc/network/interfaces, also can you report the results of ping google.com.