Comment 5 for bug 2033099

I've dug deeper. Some GUI parts (such as software updater and Online Accounts in setup) rely on NetworkManager to determine if there is an Internet connection. NetworkManager checks if it manages any interfaces that are up, and if not, reports there is no Internet.

When NetworkManager is not the one managing the interfaces, as in my case, NetworkManager erroneously reports the lack of Internet. The internet connection is fine, it's just not managed by NetworkManager.

IMO this is a serious bug that needs fixing. For Software Updater it's even worse as sometimes this component relies on NetworkManager and sometimes it does not, all in the same update run. Relying on different mechanisms for the same thing (is there Internet?) in the same component is a serious flaw IMO.

It's not just one package, it's how a group of packages works together.

There is a NetworkManager plugin for ifupdown (this emulates ifupdown, it does not use the real ifupdown), but that's incomplete. It ignores pre-up, post-up, pre-down and post-down, which were the whole reason for avoiding netplan/NetworkManager in the first place.