PK Curve type cannot be solved

I am using XDK Bosch device and I am trying to send data do my mqtt broker. My certificate is using Signature Algorithm ecdsa-with-SHA256. The used certificate uses elliptic curve P-384 defined by NIST for public key encription. As I saw, this curve type is defined in the firmware. From the certificate it gets the pk algorithm as MBEDTLS_PK_ECKEY and than fails to get the curve type. Any suggestions how to solve this problem?

Thanks in advance.