Simple Certificate Enrollment not working on ThinOS

Hi,

I'm trying to configure SCEP for our 3040 Thin Clients with ThinOS 9.1 (also tested with 8.6 and 9.0).

The client does not automatically request a certificate via MSCEP and whenever I manually try to do so via UIA, the cursor jumps into the Request-URL textbox without any error message or request attempt (no failed attempt to see on the CA server).

The URL has been specified without the protocol prefix and the webserver is reachable (tested with telnet).

Key Usage is Digital Signature and Key Encipherment with a length of 2048/4096 bit.

CA certificate hash type and values as well as the enrollment password have been set.

Does anybody experience the same issue?

Basic SCEP functionality already has been verified without TCs.

Thanks in advance!