@jcrben :
$ sudo systemctl stop NetworkManager
$ snap install --channel=1.10 network-manager
network-manager (1.10/stable) 1.10.6-1-20190619+916e95e2 from Canonical✓ installed
$ systemctl status snap.network-manager.networkmanager.service
● snap.network-manager.networkmanager.service - Service for snap application network-manager.networkmanager
Loaded: loaded (/etc/systemd/system/snap.network-manager.networkmanager.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2019-07-30 10:31:08 CEST; 1min 37s ago
Main PID: 14799 (NetworkManager)
Tasks: 4 (limit: 4915)
CGroup: /system.slice/snap.network-manager.networkmanager.service
└─14799 /snap/network-manager/412/usr/sbin/NetworkManager --config-dir=/var/snap/network-manager/412/conf.d/ --config=/snap/network-manager/412/etc/NetworkManager/NetworkManager.conf --log-leve
$ snap connections --all
Interface Plug Slot Notes
...
network-manager network-manager:nmcli - -
...
$ snap connect network-manager:nmcli
$ network-manager.nmcli d
DEVICE TYPE STATE CONNECTION
enx000ec6e241bf ethernet connected Wired connection 1
lxdbr0 bridge connected lxdbr0
lxcbr0 bridge connected lxcbr0
mpqemubr0 bridge connected mpqemubr0
virbr0 bridge connected virbr0
veth03RMIL ethernet connected veth03RMIL
wlp3s0 wifi disconnected --
maasbr0 bridge unmanaged --
mpqemubr0-dummy dummy unmanaged --
lo loopback unmanaged --
virbr0-nic tun unmanaged --
$ network-manager.nmcli c
NAME UUID TYPE DEVICE
Wired connection 1 ed72f419-a070-3d3c-9683-a3d4f33d327d ethernet enx000ec6e241bf
lxcbr0 d619a208-3d1b-466b-86f4-51725949cbcd bridge lxcbr0
lxdbr0 fc664f1f-3538-4f7c-8d11-56057307f44a bridge lxdbr0
mpqemubr0 ac07f65c-4827-4ab2-8b05-94825705bfda bridge mpqemubr0
veth03RMIL 5d84ee6f-c691-43b9-a182-b0b8742faeaa ethernet veth03RMIL
virbr0 f5ccaead-23ab-4259-aae7-67f4ab7f1dc8 bridge virbr0
Wired connection 2 b4a1ff89-2b85-37db-82ba-b651f7d5a275 ethernet --
The critical step you were missing was taking a look at the interfaces and connect the nmcli one, that is why I suggested to look at snap connections --all output. Not all interfaces are auto-connected on installation, for security reasons. Said this, it is a bit strange that that interface is auto-connected on UC systems but not on Desktop. @ijohnson maybe you know why could this be happening?
Nonetheless, you will still see apparmor denials that come from subscriptions of gnome-shell to NM’s dBus signals. The integration of the snap on Desktop is not ideal because, as explained, it is not the main target for the snap, but you should be able to use nmcli and configure the connections as desired.
Finally, I recommend that you remove the network-manager snap and then install the one from the 1.10 track. The reason is that the 1.2 snap does not try to manage ethernet by default, see https://docs.ubuntu.com/core/en/stacks/network/network-manager/docs/enable-ethernet-support for details (you need to set the ethernet.enable property).