Hi @Rip
that happens always if I start the server-daten test system (port 442, not public visible) after some hours / days inactivity with a certificate with "Must staple".
That's an IIS 10.
The application starts, but the IIS 10 doesn't have something cached.
So sending back the result to the client -> that error.
Parallel: Checking OSCP.
F5 to refresh - all works.
Same with a local installation:
MOZILLA_PKIX_ERROR_REQUIRED_TLS_FEATURE_MISSING
It's not really a problem, it's feature-specific.
Apache may have the same problem.