SpaceLogic Home controller Let's Encrypt SSL certificates

Hi all
I have installed in my home C-bus network a SpaceLogic 5200WHC2 controller .
Recently I have upgrated the firmware to version 2.01.1 successfuly . My purpose is to upload SSL certificates to ensure the remote control capability. I used dyndns.org DDNS service to obtain a host name and I have define port 443 as the remote control port . I have transferred all the above information to the controller by using SPICE software during the project transfer .
Following the upgrade and the latest project transfer the controller works fine , it is connected to c-bus network and in my local LAN and I can use all functions from my IOS mobile app and my laptop through the unit Web interface .
To ensure the remote control capability I need to purchase and install SSL certificates in the controller. To this end I decided to follow the recomendation provided in the controller manual and use the Let's Encrypt automatic alternative from the setup page of the controller Web interface. I have used and clicked the relevant buton and the unit gave a message that is contacting the Let's Encrypt servers to generate and upload the certificates . After a few minutes I receive a message that the certificate generation failed and to try later. I tried several times and in different dates but the Let's Encrypt certificate generation failed always.
This is the problem and my question is if any user has tried this Let's encrypt alternative with succes.
Why SE has incorporated this SSL generation alternative in the controller firmware , but is not working ??
I kindly ask for any assistance to this matter and information about the nature of this problem.
Thanks and regards, Christos Malandrakis.