fatal error: WiFiUdp.h: No such file or directory

[tom-eilers-nl]

compilation terminated.:
ESPHome 2026.6.0

In file included from src/esphome/components/udpserver/udpserver_component.cpp:1:
src/esphome/components/udpserver/udpserver_component.h:2:10: fatal error: WiFiUdp.h: No such file or directory:

My Yaml fille:

esphome:
name: poesp32
friendly_name: Relays

esp32:
variant: ESP32
framework:
type: arduino
cpu_frequency: 240MHZ
external_components:

• source: github://jsimonetti/esphome-udpserver
  components: [ udpserver ]

logger:
hardware_uart: UART0

ethernet:
type: IP101
mdc_pin: GPIO23
mdio_pin: GPIO18
clk:
mode: CLK_EXT_IN
pin: 0
power_pin: GPIO5
phy_addr: 1

switch:

• platform: gpio
  id: relay1
  pin: GPIO16
  name: "Relay1"
  device_class: switch
  restore_mode: RESTORE_DEFAULT_OFF
• platform: gpio
  id: relay2
  pin: GPIO17
  name: "Relay2"
  device_class: switch
  restore_mode: RESTORE_DEFAULT_OFF

udpserver:
id: my_udp_server
listen_port: 9999
on_string_data:
- then:
- lambda: |-
ESP_LOGD("udp", "Processing command: %s", data.c_str());

        if (data == "relay_on") {
          id(relay1).turn_on();
          udp.send_response("OK: Relay turned ON");
        } 
        else if (data == "relay_off") {
          id(relay1).turn_off();
          udp.send_response("OK: Relay turned OFF");
        }
        else if (data == "relay_status") {
          std::string status = id(relay1).state ? "ON" : "OFF";
          udp.send_response("Relay status: " + status);
        }
        else {
          udp.send_response("ERROR: Unknown command");
        }

mdns:
disabled: false
services:
- protocol: _udp
service: poesp32
port: "1234"
txt:
new_1: dfgf

[schluetter]

I got a similar error while trying to reimplement the Shelly 3EM Pro "emulation" on my Olimex ESP32-POE board that acts as an SML interface to the main electricity meter using ESPHome:

esphome/components/udpserver/udpserver_component.cpp.obj.d -o esp-idf/src/CMakeFiles/__idf_src.dir/esphome/components/udpserver/udpserver_component.cpp.obj -c /data/build/p70tkhar-supply/src/esphome/components/udpserver/udpserver_component.cpp
In file included from ../src/esphome/components/udpserver/udpserver_component.cpp:1:
../src/esphome/components/udpserver/udpserver_component.h:2:10: fatal error: WiFiUdp.h: No such file or directory
    2 | #include <WiFiUdp.h>
      |          ^~~~~~~~~~~
compilation terminated.

In my case I suspect that the cause for that behaviour is missing wifi support on my device. It is connected via Ethernet to the Network (also using POE for power).

Would it be possible to use a more "generic" UDP implementation? This might make it useful for a broader audience – not only those, who use wifi networking. I did look at the built-in UDP support from ESPHome, but that seems to miss some of the nicer things from this custom component (e.g., a direct response using the address and port number from the request).

I found https://community.home-assistant.io/t/marstek-venus-e-with-esphome-sml-reader-as-virtual-shelly-3-pro-em/903711/21 with an alternative implementation for Marstek Batteries and the ESPHome built-in UDP component, but I don't know if that would work with my Zendure setup. And I don't know the port where the Zendure SolarFlow2400 Pro expects the answers from the Shelly … .

[tom-eilers-nl]

I used Tasmota for my M5 Poesp32. That works. Thanks for your answer.