I have tried both configurations:
mqtt_cfg.broker.address.port = MQTT_PORT;
mqtt_cfg.broker.address.transport = MQTT_TRANSPORT_OVER_SSL;
mqtt_cfg.broker.address.hostname = MQTT_HOST;
mqtt_cfg.broker.address.uri = MQTT_BROKER_URI;
In both cases I received:
esp-tls: couldn’t get hostname for :xxxxx.s1.eu.hivemq.cloud: getaddrinfo() returns 202, addrinfo=0x0