Ethernet Webserver How to use separate HTML file instead of inline

You can try my EthernetWebServer library, which supports RP2040 + W5500 using either ArduinoCore-mbed or arduino-pico core.

Check this AdvancedWebServer example and you can either leave the html inside the .ino or split the html code to a separate .h file

LittleFS can also be used and you just load the html to a variable at the beginning, then use it as long as you'd like.

Check the similar examples written for ESP32 and ESP8266 and LittleFS

  1. FS_EthernetWebServer
  2. ESP32_FS_EthernetWebServer

Here is the LittleFS_Mbed_RP2040 library for mbed core and LittleFS for arduino-pico core