Access error https ucs univention

Hello good,
I have a ucs univention instance integrated with owncloud and onlyoffice, I could access only in http but to access via https install the Let’s Encrypt app and the domain of the ucs instance was configured: “ucs-2153.serconsult.intranet”, everything worked fine 1 week, now I can only access through http and not https, when I enter the ucs app platform I see an error.

I wait for the guidance to solve the problem.

I attach the image of the app problem
error

The answer seems to be in the error message.

You are trying to get a certificate for an internal domain name which is invalid as a public domain.

Let’s encrypt will not issue a certificate for that name. I expect you would have to do your own certificate management for that server or assign it another domain name that is valid for the public internet and setup let’s encrypt for that name.