The free certificate issued by Let’s encrypt lasts 3 months after which it must be renewed, before the deadline. Through its powerful operating system, Synology Nas integrates this “process” and makes it automatic and very easy to manage. If you have a domain and use it for web hosting or simply to access your Synology Nas, it is possible to renew the certificate following the images in this guide that I have carefully prepared for you. I will now explain to you step by step what needs to be done.
Step 1: Log into your Synology Nas using your root credentials. Go to Control Panel/Security/Certificate. Right click on the domain you want to renew. Click “Renew Certificate”. Follow the instructions in the image below.
Step 2: Be sure to open your Port through your router settings. You have to open TCP/UDP ports 80 and 443. Every router has its own design interface regarding this aspect. At the moment I am using a D-Link router.
Step 3: Click Apply and in maximum 5-10 seconds after that your Certificate will be automatically renewed.
Warning: Whenever your let’s encrypt certificate approaches the end of the 3 month period, remember to do this simple operation that will take you less than a minute. When your let’s encrypt certificate is about to expire, you will see the green lock before the domain name turn red. This being said, know that you can still renew your certificate before it expires even if the lock before your domain name is still green/hasn’t turned red yet. You don’t have to wait for the lock to turn red so you can renew your certificate.
TLS-SNI-01 Troubleshooting: If you get an email from let’s encrypt about TLS-SNI-01 end of life please refer to this article: How to Solve Synology Let’s Encrypt TLS-SNI-01 end of life.