EDIT: So for shits and giggles I created a new duckdns domain and set it up. Works perfectly with HA. The one above is linked to the wrong cert. Can we get a way to force a new cert?
I have been having the same issue too…I am locked out of lets encrypt at the moment for generating too many certificates…I have removed DuckDNS and reinstalled it several times now…The certificate says its valid until 26th August but on
My easiest solution for that would be to instal the IDE add-on (https://github.com/hassio-addons/addon-ide) and backup the files, delete them and you can see if it generates a new cert to fix the problem when you restart the duckDNS add-on.
If you use samba you can enable the ssl directory in the samba addon options. Set “ssl”: true, save, restart the addon and then you will see it as another shared directory along with the others. You may want to disable it again once you are done poking around.