Now (after using the cert from that command) I get: What might cause this?

I want to connect with my ESP32 and a Quectel modem to an MQTT broker using TLS (port 8883). I can't get a working combination of code.

What I have (based on the SSL example):


// Configure the MQTT client
esp_transport_handle_t at =
esp_transport_at_init(Modem::getInstance().getDCE());
if (!at ...

I'm trying to send a 0x03 Read holding registers request as a Modbus master to the listening slaves. What is the best way to send a request (the read request), wait for the response, and then read it? I'm stuck at waiting for the response. Could you please help me further?

I tried a fixed delay ...

#define ETH_PHY_ADDR 0
#define ETH_PHY_RST_GPIO GPIO_NUM_17
#define ETH_PHY_POWER_GPIO GPIO_NUM_2
#define ETH_PHY_MDIO_GPIO GPIO_NUM_18
#define ETH_PHY_MDC_GPIO GPIO_NUM_23

esp_err_t Ethernet::init() {
esp_err_t err;

// Turn on LAN8720
gpio_set_direction(ETH_PHY_POWER_GPIO, GPIO_MODE_OUTPUT ...

I'm using an LAN8720 chip connected by a custom PCB, which works fine when I'm not using GPIO4 for UART.

TX EN: IO21
TX D0: IO19
TX D1: IO22
RX D0: IO25
RX D1: IO26
CRS DV: IO27
MDIO: IO18
MDC: IO23
REF CLK: IO0
RESET: IO17
LAN8720 ON: IO2

I'm using an ESP32-WROOM-U. When I try to use GPIO4 for UART when I have Ethernet enabled, it can't get an IP. Why is this? How can I fix this?