https – iOS Safari not accepting certificates issued by custom CA

I’m trying to make iOS Safari accept an https website that runs a certificate I signed with my own CA.

My CA cert is here: https://gist.github.com/BenMorel/014d7bd7802b75eec78b0bc0bad7e4e1

When I import this CA in Chrome / Edge / Firefox, on Windows & Linux, all the browsers accept the certificate and allow me to browse my website with no warning.

On iOS, however, I can’t make this work. I downloaded the CA from the URL above, then followed all the steps listed here.

The CA is now listed in the Configuration Profiles, and enabled in the Certificate Trust Settings. With that done, I’m still getting the following errors:

  • iOS Safari:

    Safari can’t establish a secure connection to server

  • iOS Chrome:

    ERR_SSL_PROTOCOL_ERROR

  • iOS Firefox:

    An SSL error has occurred and a secure connection to the server cannot be made.
    NSURLErrorDomain

Again, this works fine with all desktop browsers. What did I miss?