I have been using lets encrypt for awhile, without any issues. In fact it is working fine when viewed via browser.
After renewing my certificate, I am no longer able to run the IOS app, keep getting a certificate error. I have uninstalled twice, hoping that all the setting would be deleted, to no avail.
@petro@petermj luckily for me, everything works. About two weeks after I made the original post, an update to IOS was released, and I think there was a Hass update as well (I don’t remember which). Anyway, I reinstalled the IOS app a third time and it started working again. I wish I would have recorded the versions of hass and the IOS app in my original message.
I just made a whole new ddns domain and it works. My issues is that the hass.io addon thinks the cert is correct and up to date. Everything connecting to it says that it is NOT up to date. Really frustrating. It has to be a ddns hassio add on bug.