Dash & Yandex IOT core does not work together

  1. My goal is: send data to mdash and use mqtt Yandex iot broker
  2. My actions are: I have the next config mqtt section and dash section
	"mqtt": {
		"enable": true,
		"server": "mqtt.cloud.yandex.net:8883",
		"client_id": "",
		"reconnect_timeout_min": 2,
		"reconnect_timeout_max": 60,
		"ssl_cert": "",
		"ssl_key": "",
		"ssl_ca_cert": "rootCA.crt",
		"ssl_cipher_suites": "",
		"ssl_psk_identity": "",
		"ssl_psk_key": "",
		"clean_session": true,
		"keep_alive": 60,
		"will_topic": "",
		"will_message": "",
		"will_retain": false,
		"max_qos": 2,
		"recv_mbuf_limit": 3072,
		"require_time": false,
		"cloud_events": true
	"dash": {
		"enable": true,
  1. The result I see is: if dash.enable=true, I cannot connect to yandex iot
[Jul 17 18:33:36.432] mgos_mqtt_conn.c:471    MQTT0 connecting to mqtt.cloud.yandex.net:8883
[Jul 17 18:33:36.479] mongoose.c:4912         0x3ffef56c ciphersuite: TLS-ECDHE-RSA-WITH-AES-128-GCM-SHA256
[Jul 17 18:33:36.813] mongoose.c:4912         0x3ffef56c x509_verify_cert returned -9984
[Jul 17 18:33:36.813] mongoose.c:4912         0x3ffef56c   The certificate is not correctly signed by the trusted CA

If dash.enable=false, device send data to yandex iot normally.
If mqtt.enable=false, device work with mdash normally.
4. My expectation & question is: My suggestion is: mdash and mqtt used the same parameter ssl_ca_cert - CA certificate, but dash have get it from ca-bandle , and mqtt from Yandex. Yandex have self-signed certificate. I have tried to add yandex certificate to ca.pem from ca-bandle but receive the problem with connection with dash or yandex depends on adding certificate to begin or end of ca.pem.
My question: how to config mdash and mqtt to work with yandex and mdash simultaneously