Carbonio CE 25.6.1 Fresh Install - Let's Encrypt

Hi all,

first of all: Many thanks to bring up a alternative solution to my beloved but no longer free of charge Zimbra Solutions! 
Its a pitty they made the step, but hey - now I have a much more modern solution to work with!

Why free of Charge? Because I have only 3 "real users" (all family) and multiple historic mail domains to manage and use. 

So I gave Cabonio a chance and hey - it looks great! I had some issues with the foundation of Ubuntu 24.04 so I went back to 22.04 and that was smooth.
Also the automatic script based Installation is great!!! Wow how luxury!!! 😀

I made all my required settings and boom - the first emails were sent in and out.

So I continued with the installation/configuration and saw the great functionality of Let's Encrypt. At the end I will still use my already renewed and for another 4 years running SSL Certificate but for the future - this is my way to go.

Generating the SSL Certificate through the AdminPanel worked (after some challenges) fine - do I really need to keep Port 80 open or is there a workaround?

But I do have one challenge with the installed certificate. The Emails tell me all is good and my certs are valid till 21/09/2025 and also on the AdminPanel under "Virtual Hosts & Certificate" I see the CN, Subject, Issuer and validity dates filled out. 
But the initial browser access still presents me the self signed Zextras Carbonio CA.

What is wrong?! And even more interesting: What do I need to do the certificate from LetsEncrypt will be used?

Thanks for your feedback.

Alexander