Comment 8 for bug 1772859

"We understand Network Manager is good for desktop but not servers." I would not phrase it this away. On Ubuntu, Desktop defaults to NetworkManager and Server defaults to netplan&networkd. Previously we defaulted to NetworkManager & ifupdown.

"But given the stability NetworkManager is bringing in and ease of use across different operating systems, i assume users are not restricted not to use NetworkManager for servers." I would significantly challenge those statements. NetworkManager is extremely flakey, and consistently fails to reliably bring complex network configurations up, as exercised by our stress testing. It also is far from easy to use. Wrt. users restrictions, Ubuntu tries to guide users to an obviously correct, easy, default and obvious ways of doing things. However, we do indeed allow users to break their systems and keep all the broken pieces.

"The reason being we going with network manager as explained is to reuse the code for all distros." I don't believe that's the right thing to do, as that does not validate how end customers will use respective distros on z hardware. All customers will most likely use whatever each distro installer sets up, and will not tear that out and go out of their way to use networkmanager in a lowest common denominator configuration (e.g. Ubuntu's network-manager is patched, and is at a different version level than other distros)

"Note : Netplan is not present/installed in our ubuntu. So by default we are expecting network manager to work."

After installing a system, if you want netplan to be out of the way - and have the ability to use straight-up netwokrd/NM/etc, I'd rather recommend removing /etc/netplan/* configs and rebooting, without uninstalling netplan.io package. This would guarantee that interfaces are undeclared as managed-on-unmanaged by anything.