I have commented out both "auto eth0" and "iface eth0 inet dhcp": problem remains. In attachment the NetworkManager logs.
I have compared with diff NetworkManager.conf with the one on my desktop PC (where everything works) and it is identical: both managed=true.
So I don't have any clue while the NetworkManager connects on the (older) desktop and does not connect on the (newer) laptop.
I have commented out both "auto eth0" and "iface eth0 inet dhcp": problem remains. In attachment the NetworkManager logs.
I have compared with diff NetworkManager.conf with the one on my desktop PC (where everything works) and it is identical: both managed=true.
So I don't have any clue while the NetworkManager connects on the (older) desktop and does not connect on the (newer) laptop.