After trying to update a few of our clients Synology NAS SSL certificates it was clear there was an issue. They were all receiving the response “NO RESPONSE FROM DESTINATION SERVER. PLEASE TRY AGAIN LATER.” Then I remembered that the Let’s Encrypt DST Root CA X3 certificate had expired on September 30, 2021 and that had caused some other issues. Luckily there is a simple solution, simply update your NAS to at least version DSM 6.2.4 Update 2

  1. Head to Control Panel
  2. Select Update & Restore
  3. Select Download and then Update Now
  4. You could also update to DSM 7 if you have a compatible NAS
  5. Then try to renew your certificate again by heading to Security -> Certificates