Can you explain why you have configured eth0 that way? I believe that it may be confusing NetworkManager.
I do agree that there seems to be an error in terms of eth0 initially being considered conected when a cable is not present. Please confirm: that's the problem, yes? On an initial boot, without a cable being plugged into the wired port, eth0 is considered connected?
Is this your /etc/network/ interfaces file?
auto lo
iface lo inet loopback
iface eth0 inet static
address 134.219.128.31
netmask 255.255.252.0
gateway 134.219.128.1
auto eth0
Can you explain why you have configured eth0 that way? I believe that it may be confusing NetworkManager.
I do agree that there seems to be an error in terms of eth0 initially being considered conected when a cable is not present. Please confirm: that's the problem, yes? On an initial boot, without a cable being plugged into the wired port, eth0 is considered connected?