[Discuss] Ubuntu won't talk to my router over the wire

[Richard Pieri]

The most common cause of network weirdness that I've recently
experienced is NetworkManager. It has a habit of overwriting perfectly
good, working network configurations with configurations that don't
work. I typically remove NetworkManager when possible, and disable the
daemon startup scripts when not.

Number two is is mismatches between actual hardware and the rules in
/etc/udev/rules.d/*-persistent-net.rules. The fix is to remove the
offending rules from this file (or all rules for that matter), reboot,
and reconfigure the interfaces.

-- 
Rich P.