Synology Directory Server create new certificate

check Synology Directory Server Package domain controller name.  For this example controller.test.local. Check your own domain controller name and use accordingly. 

• Control Panel, Security, Certificate, Settings, Advanced, Create Certificate Signing Request (CSR).
• Fill in all fields, under common name for example controller.test.local 
• following the steps and a zip file is created, download locally. 
• Unzip the zip file, 2 files are created server.key and server.csr
•  create in same directory following file and change accordingly; vi san.cnf

[san_sec]subjectAltName = DNS:controller.test.local

•  run following command:

openssl x509 -req -in server.csr -signkey server.key -out controller.test.local.crt -days 365 -extfile san.cnf -extensions san_sec

• controller.test.local.crt is created in the same directory. 
• Control Panel, Security, Certificate, Add, add a new certificate, next, import certificate, next

Private key: server.key

Certificate: controller.test.local

• A new certificate is created
• Settings, Synology Directory Server choose newly created certificate