[CentOS] CentOS 7, systemd, NetworkMangler, oh, my

My manager tells me a system in the datacenter is down. I go down there,
and plug in a monitor-on-a-stick and keyboard. It's up, but no network. I
try systemctl restart NetworkManager several times, and ip a shows *no*
change.

Finally, I do an ifdown, followed by an ifup, and everything's wonderful.

My manager thinks that the NM daemon thinks everything's fine, and
there've been no changes, so it does nothing. He suggests that it might
have to be stopped, then started, rather than restarted.

This is completely unacceptable behavior, since it leave the system with
no network connection. Pre-systemd, as we all know, restart *RESTARTED*
the damn thing.

Is there some Magic (#insert "pixie-dust-sparkles") incantation, either
restarting NetworkManager, or using nm-cli, to force it to perform the
expected actions?

Btw, if this is supposed to be part of the "hide stuff, desktop Linux
users don't need to know this stuff", this is a *much* worse result.

    mark (and yes, my manager's truly aggravated about this, also)