SSL_CTX_set_mode
SSL_CTX_set_mode(ctx, SSL_MODE_DTLS_SCTP_LABEL_LENGTH_BUG);
SSL_CTX_set_mode(ctx, SSL_MODE_ASYNC);
SSL_CTX_set_mode(ctx, SSL_MODE_DTLS_SCTP_LABEL_LENGTH_BUG);
SSL_CTX_set_mode(ctx, SSL_MODE_ASYNC);
SSL_CTX_set_mode(ctx2, SSL_MODE_ASYNC);
SSL_CTX_set_mode(client_ctx, SSL_MODE_DTLS_SCTP_LABEL_LENGTH_BUG);
SSL_CTX_set_mode(server_ctx, SSL_MODE_DTLS_SCTP_LABEL_LENGTH_BUG);
SSL_CTX_set_mode(conn->ssl_ctx, SSL_MODE_AUTO_RETRY);