network-manager does not handle wired connections without netplan

[Esokrates]

Take a fresh installation of Ubuntu and remove the package netplan.io.
Now you will observe, that network-manager no longer detects wired connections.

Installing ifupdown instead of netplan does not help this situation.

In debian sid networkmanager detects the wired connections, without netplan or ifupdown!

So it seems to me something is wrong with ubuntu packages / configuration.

Also installing netplan.io is not sufficient for networkmanager to detect wired connections again, the config file /etc/netplan/01-network-manager-all.yaml does have to contain the following lines:

# Let NetworkManager manage all devices on this system
network:
  version: 2
  renderer: NetworkManager

Tested an XPS 13 9360 with both DA200 Adapter for LAN connection and Android USB tethering connection, both not configured automatically by networkmanager without netplan, while it works perfectly fine in Debian.

Tested with Ubuntu 19.10 and Ubuntu 20.04.