Hi @EvgeniyVasyliev
The error you are getting means that you have received a fatal alert from the server.
This fatal alert was sent after the server received the ClientHello message from your client.
This means that the server couldn’t find common parameters for a TLS handshake. Usually it is the server can’t support the proposed ciphersuites, however it could be other cases such as unsupported eliptic curves and hashes.
However, from your log, I see that your client only suggests c02c (MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384) and c02b (MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256)
So I am assuming your server only has RSA signed certificates. You can try using the SSL Labs server test to see what ciphersuites this server supports
Regards,
Mbed TLS Support
Ron
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