`//Network event handler
void networkEvent(arduino_event_id_t event) {
 switch (event) {
 case ARDUINO_EVENT_ETH_START:
 Serial.println("ETH Started");
 ETH.setHostname(config.mdns_hostname);
 break;
 case ARDUINO_EVENT_ETH_CONNECTED:
 Serial.println("ETH Connected");
 eth_connected = true;
 break;
 case ARDUINO_EVENT_ETH_GOT_IP:
 Serial.println("ETH Got IP: " + ETH.localIP().toString());
 eth_IP = true;
 break;
 case ARDUINO_EVENT_ETH_LOST_IP:
 Serial.println("ETH Lost IP");
 MDNS.end();
 eth_IP = false;
 mdnsInitialized = false;
 break;
 case ARDUINO_EVENT_ETH_DISCONNECTED:
 Serial.println("ETH Disconnected");
 eth_connected = false;
 break;
 case ARDUINO_EVENT_ETH_STOP:
 Serial.println("ETH Stopped");
 eth_connected = false;
 eth_IP = false;
 MDNS.end();
 mdnsInitialized = false;
 break;
 case ARDUINO_EVENT_WIFI_STA_CONNECTED:
 Serial.println("WiFi connected.");
 digitalWrite(WIFI_LED, HIGH);
 wifi_connected = true;
 break;
 case ARDUINO_EVENT_WIFI_STA_GOT_IP:
 Serial.print("WiFi IP address: ");
 Serial.println(WiFi.localIP().toString());
 wifi_IP = true;
 break;
 case ARDUINO_EVENT_WIFI_STA_DISCONNECTED:
 if (wifi_connected) Serial.println("WiFi disconnected.");
 wifi_connected = false;
 wifi_IP = false;
 MDNS.end();
 mdnsInitialized = false;
 digitalWrite(WIFI_LED, LOW);
 break;
 case ARDUINO_EVENT_WIFI_STA_START:
 Serial.print("WiFi Started. Connecting to ");
 Serial.println(config.ssid);
 break;
 case ARDUINO_EVENT_WIFI_STA_STOP:
 Serial.println("WiFi Stopped.");
 break;
 case ARDUINO_EVENT_WIFI_READY:
 Serial.println("WiFi Ready.");
 break;
 default:
 Serial.printf("Got other WiFi event: %u\n", event);
 break;
 }
}`
Relevant code in setup():
`if (!ETH.begin(ETH_PHY_LAN8720, 0, 23, 18, 5, ETH_CLOCK_GPIO17_OUT)) {
 Serial.println("Ethernet failed to start");
 }
 WiFi.begin(config.ssid, config.password);
 esp_sntp_servermode_dhcp(1);
 sntp_set_time_sync_notification_cb(timeavailable);
 configTime(0, 0, config.ntp_server, ntpServer2);`
Eth related code in main loop:
`//enable wifi when no Eth
 if (!eth_connected && !wifiEnabled) {
 if (wifiSta) {
 WiFi.mode(WIFI_STA);
 WiFi.begin(config.ssid, config.password);
 wifiEnabled = true;
 EthStartFlag = false;
 }
 }
 //disconnect WiFi when Eth connected.
 if (eth_connected && wifiEnabled) {
 WiFi.disconnect(true);
 WiFi.mode(WIFI_OFF);
 wifiEnabled = false;
 }
 if (!mdnsInitialized) {
 if (eth_IP || wifi_IP) {
 if (!MDNS.begin(config.mdns_hostname)) {
 Serial.println("Error setting up mDNS for Ethernet");
 } else {
 Serial.println("mDNS started as " + String(config.mdns_hostname) + ".local");
 MDNS.addService("http", "tcp", 80);
 MDNS.addService("ws", "tcp", 80);
 mdnsInitialized = true;
 }
 }
 }`

From serial:
`UTC Time: 2025年09月24日 05:05:06 WiFi IP address: 192.168.55.248 Free heap: 163 KB
ETH Connected
WiFi disconnected.
WiFi Stopped.
Got other WiFi event: 100
ETH Disconnected
UTC Time: 2025年09月24日 05:05:16 WiFi Status: 6, SSID: network, Password: network1 Free heap: 201 KB
Rebooting Eth. E (161511) esp.emac: emac_esp32_rm_mac_filter(199): failed to remove MAC filter
E (161511) esp_eth: esp_eth_ioctl(540): remove mac address from filter failed
E (161515) esp_eth.netif.netif_glue: eth_set_mac_filter(58): failed to delete mac filter
E (161523) esp_netif_lwip: Failed to remove multicast filter for IPv4
ETE (161531) FreeRTOS: Fatal error: TLSP deletion callback at index 0 overwritten with non-excutable pointer 0x726f736e
abort() was called at PC 0x4008f890 on core 1
Backtrace: 0x4008e718:0x3ffb2050 0x4008e6dd:0x3ffb2070 0x40094a65:0x3ffb2090 0x4008f890:0x3ffb2110 0x4009047a:0x3ffb2130 0x40091392:0x3ffb2150 0x4014893e:0x3ffb2170 0x40148b5a:0x3ffb2190 0x400ea09f:0x3ffb21b0 0x400e5c3e:0x3ffb21d0 0x401081c0:0x3ffb2270 0x4008f561:0x3ffb2290
ELF file SHA256: 0f1ccaedf
Rebooting...
E (48) task_wdt: esp_task_wdt_init(517): TWDT already initialized
*** BOOT ***
Version: 0.6.18: Eth Reboot code updated.`