Why is my ethernet connection connecting and disconnecting repeatedly?

Solution 1:

correct me if im wrong but it looks like you are trying to use a shared connection. There is a bug in oneiric regarding this. Please look at a different answer for a workaround and the link to the bug. Wired Connection shared with other computers connects then disconnects in the nm-applet The workaround is to set IPv6 to ignore when you edit the connection and then do sudo killall dnsmasq