Comment 19 for bug 2060311

> In the past it was okay to NOT have "optional: true" set for both: encc000 and encc000.2653 (and I found that logical, since both interfaces are needed in a VLAN context).
>
> Knowing now what's missing, I could live with that (even if it's a change in behavior).

Interesting.. I suspect some infrastructure changes here. The default for systemd-networkd-wait-online is to wait on the "degraded" operational state, i.e. having a link-local address assigned to the interface.

If there is SLAAC or IPv6 RA enabled on the other side of "encc000", the interface might come online without "optional: true". But lacking such setup, it would be stuck in the "configuring" state, as it waits for an (IPv6) link-locaL address, putting it as "optional: true" helps in that case with our recent changes.