Hello @nimeut, I'm having exactly the same problem as you on macOS (unable to select the certificate), but on iOS, the certificate can be selected when the page loads. However, in macOS settings, the certificate generated by ACME is definitely there (System Settings > General > Profiles > [NAME] > ACME Certificate). In the WWDC 22' video, it's stated that mTLS can be used with Safari. I’ve tried several methods for the IdentityPreference, but none of them work (with/without protocol, with/without port, etc.). In my opinion, the documentation is far too incomplete, and the use cases are too limited (no third-party apps like Chrome on macOS, even with AllowAllAppsAccess, etc.), so I think I’ll switch to SCEP. I find it unfortunate that Apple hasn’t made any progress on this topic since 2022, even though SCEP has been deprecated in the documentation for some time now.