Let's Encrypt/DuckDNS/Hass.io error

Don’t think a device cache is relevant is it as the router does the routing doesn’t it not? I just denied my Mac access to the internet and without any restart stuck the duckdns address in and it went straight to it.

I had already got the router set as the first dns server though so I could call local devices with hostname.home rather than their IP, don’t know if that made a difference.

Good evening all,
It’s just a couple of weeks that i’m playing with Hass.io, so I’m just entering on this world.
I thought it was worth to write here because it is in regards of this topic, but let me know if it is wrong, and if so tell me what I should do.
I have read entirely this topic, and I think everything is working properly, but I would like to have a confirmation on this from someone who has more knowledge.
Long story short: I can access to home assistant from anywhere and I don’ t get any message about a not secure connection (that’s why I’m saying “everything is working properly”), but I’m noticing that the DuckDNS add-on is always off and if I try to turn it on, the log says:
ERROR: Lock file ‘/data/workdir/lock’ present, aborting.

Is this normal? Does DuckDNS has to stay off?
Thank you in advance