Hoping this is my issue too!
Have not been able to access my Home Assistant via Google Home/Assistant for going on 24 hours now.
I notice accessing via my duckdns address is a bit hit or miss too.
Going to bed now. Hopefully it’ll be resolved by morning…
reading all above points to a dns issue, which would be a router issue.
Same here since yesterday around noon CEST. Thanks for posting!
Same here. According to their faq, they track their service health at http://www.intodns.com/duckdns.org and you can see many errors there. Not sure how to report it to them though…
+1 same problem since 1.October
Arround 1/4 of the last 24h i have no connection. The 2 last weeks, i had just few connection-problems and before everithing was fine.
It’s not a router issue, it’s a propagation issue of Duckdns. Other DNS authorities loosing intermittent DNS entries…
Check it here
https://dnspropagation.net/
I have the same issue, just that google thought to make my life hell and added Deceptive website label to my HA, so I lost many hours trying to figure out if I have been hacked, when in fact it was duckdns dying out that most likely generated all the problems.
Changing dyndns now means reconfiguring lots of stuff for everything manually linked but there is no way around it apparently.
I gave Dynu DDNS a try, for a day it works perfectly, the official version does not work tho, so you need to download and apply the fix in these comments: Addon fails to start: s6-overlay-suexec: fatal: can only run as pid 1 · Issue #4 · koying/ha-addons · GitHub before installing it.
From a machine outside your lan you should run
dig +trace mydomain.duckdns.org
And post the results.
Same problem here started 1 oct. Reset everything.(restored backups) factory reset router/modem. days/night work.
Didn’t work. sometimes I get connection and 2 min later its gone. Hope they fix this.
I run three HA setups at three different locations with three different routers, all with a DuckDNS setup. All facing the problem since yesterday… definitely not a „router issue“.
Yepp, same issue since yesterday. 
Having issues with duckdns resolving, been about 2nd day now, hence reaching out.
I am using haproxy, and needed to find out where the issue could be, thanks for raising this post.
Weird, i have no problems at all with duckdns.
But with google assistant i can’t sync anymore…
I’m also no longer able to connect to my test system using duckdns!
I thought my domain is maybe not synced with IP from my router and tried to open duckdns.org.
But i also can’t open the website
How can i change back to local URL until the service is working again?
I switched before years from duckdns to cloudflare since the problems with duckdns come again and again.
If you have a spare domain, you can use this as an alternative to duckdns:
Works like a charm, i had 0 problems since i switched.
Now I think about it, it started for me around noon as well. Something might have been deactivated/changed around noon at the 1st of October on their end 
I tried to find a channel where I can find some updates on the issue by the DuckDNS-team, but I cannot find it.
yes it started 18 hours ago with google assistant.
But did not notice yet any connection issue’s with duckdns to any of my hass servers.
Same problem here. I can only reach my home assistant locally. The problems started yesterday. I’ve restarted duckdns several times but unfortunately it won’t work.
Yes right now i can’t connect either… weird…
Is there a file where the URL is stored in order to change it back to homeassistant.local:8123?
In mean somewhere in the config folder or another folder which can be accessed via network share.
