I got problems with my custom domain setup on readthedocs. Suddenly custom domain (https://docs.joinrpg.ru) stops working with SSL_ERROR_NO_CYPHER_OVERLAP.
Variois SSL checkers report that they "Failed to communicate with the secure server".
Readthedocs panel say that SSL certificate status: restricted_name_failure: Use of one or more domains on the certificate is restricted.
There was partial block by local authorities of readthedocs in Russia, but it (a) was on DNS-level (b)seems to be solved now, and (c) problem seems to reproduce outside russia.
What can I do to diagnose issue?
It was a bug with Cloudflare doesn't allow to issue certificates for "ru" domain zone. It have been switched to Let's encrypt thanks to readthedocs team.