[radsecproxy] Error while connecting using TLS 1.3

Hello, I'm currently setting up our radsecproxy for the use with Eduroam. The TLS connection seems to be not possible though. When I try to start the daemon, I get the following error in the log file: sslreadtimeout: SSL: error:14094418:SSL routines:ssl3_read_bytes:tlsv1 alert unknown ca My certificate is definetly valid and I've configured the right certificate chain. When I try to connect to the federation radius server (by DFN here in Germany) manually with openssl s_client it works, but only using tls 1.0,tls 1.1 and tls 1.2. It does not work with TLS 1.3. Any idea why this is happening? So the real problem is: It works with all other TLS versions, but not 1.3. Is there a way to force OpenSSL lib to use only 1.2 somehow? Thank you in advance to you all. Marc Sauer -- Marc Sauer Linux Systems Administrator Kunsthochschule für Medien Köln/ Academy of Media Arts Cologne Peter-Welter-Platz 2 50676 Köln https://www.khm.de https://en.khm.de