I was setting up SSL for a domain using cloudflare along with nginx-acme and nginx-proxy but I got error ERR_SSL_VERSION_OR_CIPHER_MISMATCH when testing.

Checking the container logs, everything looks alright.

By using SSL Labs toolkit, it shows error “Failed to communicate with the secure server”:

Looking it up, I found

which links to

Then I found the root cause was I was using a multi-level subdomain:

One easy way to fix it is to merge the multiple levels from <subdomain1>.<subdomain2> to <subdomain1>-<subdomain2>.

But sometimes we do need multi-level subdomains. For example, when we deploy L2s for our clients. We want them to get resource URLs such as:

In that case, we will use Cloudflare’s Advanced Certificates add-on feature that covers more than one level of subdomain.

One we purchased the package, we need to order those advanced certificates such as:

Then we can use the feature to issue certs when it becomes active:

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