ESP32 MQTT multiple broker setup - ssl

Question

I am trying to connect to 2 MQTT brokers at the same time using ESP-IDF.
One over TLS port 8883 and the other is not secure on port 1883.
I have declared 2 client instances, but somehow i cannot get them connect to the brokers.
If I comment out one or the other, it works just fine.
Source Code:
// Device manager configuration
esp_mqtt_client_config_t mqtt_device_manager_cfg = {
.uri = MQTT_DEVICE_MANAGER_URI,
.port = MQTT_DEVICE_MANAGER_PORT,
.username = (const char*) device_UUID,
.password = MQTT_DEVICE_MANAGER_PASSWORD,
.client_id = (const char*) device_UUID,
.disable_clean_session = 1,
.cert_pem = client_cert_pem,
.transport = MQTT_TRANSPORT_OVER_SSL
};
device_manager_mqtt_client = esp_mqtt_client_init(&mqtt_device_manager_cfg);
esp_mqtt_client_register_event(device_manager_mqtt_client, ESP_EVENT_ANY_ID, mqtt_device_manager_event_handler, NULL);
esp_mqtt_client_start(device_manager_mqtt_client);
// MQTT configuration
esp_mqtt_client_config_t mqtt_cfg = {
.uri = MQTT_URI,
.port = MQTT_PORT,
.username = MQTT_USERNAME,
.password = MQTT_PASSWORD,
.transport = MQTT_TRANSPORT_OVER_TCP
};
mqtt_client = esp_mqtt_client_init(&mqtt_cfg);
esp_mqtt_client_register_event(mqtt_client, ESP_EVENT_ANY_ID, mqtt_event_handler, NULL);
esp_mqtt_client_start(mqtt_client);
Errors:
E (5078) esp-tls: mbedtls_ssl_handshake returned -0x2700
I (5078) wifi:I (5078) esp-tls: Failed to verify peer certificate!
int: state=0 i=0
I (5078) esp-tls: verification info: ! The certificate is not correctly signed by the trusted CA
E (5088) esp-tls: Failed to open new connection
E (5098) TRANS_SSL: Failed to open a new connection
E (5098) MQTT_CLIENT: Error transport connect
Somehow it seems that the non secure client, thinks it is secure and is trying to use the certificate, which it should not.
What am I doing wrong?

Answer 1

Somehow it works, if I remove the .cert_pem value.