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.