My problem was solved below.

https://github.com/m5stack/M5Stack/tree/master/examples/Modules/W5500

https://github.com/m5stack/m5stack-documentation/issues/4

I got the same problem.
I changed the rename of Serial2 and fixed it.

HardwareSerial Serial2(2);
→HardwareSerial Serial2_(2);

And, Arduino Example page in M5Stack LAN Module is "Page not found".
M5Stack-Admin,I want you to correspond.
https://github.com/m5stack/m5stack-documentation/blob/master/en/product-documents/modules/m5stack_lan_module.rst

I found an example of W5500, but it did not work.

W5500 example is
https://github.com/adafruit/Ethernet2

But,I get the following error in my environment.

Failed to configure Ethernet using DHCP

My code is

#include <SPI.h>
#include <Ethernet2.h>

byte mac[] = {  
  0x00, 0xAA, 0xBB, 0xCC, 0xDE, 0x02 };


void setup() {
  Serial.begin(115200);
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // no point in carrying on, so do nothing forevermore:
    for(;;)
      ;
  }
  Serial.print("My IP address: ");
  for (byte thisByte = 0; thisByte < 4; thisByte++) {
    Serial.print(Ethernet.localIP()[thisByte], DEC);
    Serial.print("."); 
  }
  Serial.println();
}

void loop() {

}

I would like to try "LAN Module with W5500 Chip".
Where is LAN Module example??