C 1 июня Let's Encrypt переходит на протокол ACME2.
А Synology использует ACMEv1.
По крайней мере на софте DSM6.1-15284 Update 3.
Кто то пользуется сторонними средствами получения сертификата?
Beginning June 1, 2020, we will stop allowing new domains to validate usingthe ACMEv1 protocol. You should upgrade to an ACMEv2 compatible client before
then, or certificate issuance will fail. For most people, simply upgrading to
the latest version of your existing client will suffice. You can view the
client list at: https://letsencrypt.org/docs/client-options/
If you're unsure how your certificate is managed, get in touch with the
person who installed the certificate for you. If you don't know who to
contact, please view the help section in our community forum at
https://community.letsencrypt.org/c/help and use the search bar to check if
there's an existing solution for your question. If there isn't, please create
a new topic and fill out the help template.
ACMEv1 API deprecation details can be found in our community forum:
https://community.letsencrypt.org/t/end-of-...plan-for-acmev1
As a reminder: In the future, Let's Encrypt will be performing multiple
domain validation requests for each domain name when you issue a certificate.
While you're working on migrating to ACMEv2, please check that your system
configuration will not block validation requests made by new Let's Encrypt IP
addresses, or block multiple matching requests. Per our FAQ
(https://letsencrypt.org/docs/faq/), we don't publish a list of IP addresses
we use to validate, and this list may change at any time.
To receive more frequent updates, subscribe to our API Announcements:
https://community.letsencrypt.org/t/about-t...ements-category
Thank you for joining us on our mission to create a more secure and privacy-
respecting Web!