Adding a Let’s Encrypt cert to a Synology NAS

1. Forward 80 and 443 to 80 and 443 on your router
2. Install the Synology WebStation package
3. Turn off

Automatically redirect HTTP connections to HTTPS  in the DSM Control Panel –> Network –> DSM Settings.
4. Start the WebStation package
5. Create a Virtual Host with your DynDNS domain name as host
6. Ensure the backend server and PHP is set, along with checking the box for port 80/443. Setting not configured for PHP is fine.

6. Launch the Control Panel app and go to Security => Certificate => Addand follow the instructions of the wizard. 

7. Done!