ESP32 RFID员工考勤系统闲置数小时后无法读取标签问题求助

我最近在给员工做一套打卡系统，用ESP32搭配RFID模块实现上下班打卡功能——设备连上WiFi后，刷员工的RFID标签就能把当前时间上传到我的线上数据库。

测试阶段我时不时刷一下标签，系统运行得特别顺畅，完全没出过问题。但只要把设备闲置几个小时，再去刷标签就一点反应都没有了，感觉设备像是冻住了一样。

我的代码逻辑很简单：先连接WiFi，检测到新的RFID标签后发起HTTP请求上传数据，同时触发蜂鸣器提示打卡成功。下面是我移除敏感信息后的代码：

#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <HTTPClient.h>
#include <SPI.h>
#include <MFRC522.h>

// WiFi credentials and server details
const char* ssid = "-BV";
const char* password = "";
const char* serverName = "";
String apiKeyValue = "tPmAT5Ab3j7F9";
String sensorName = "RFID";
String sensorLocation = "Office";

// RFID reader pins
#define SS_PIN  5  // ESP32 pin GPIO5 for RFID-RC522
#define RST_PIN 27 // ESP32 pin GPIO27 for RFID-RC522
MFRC522 rfid(SS_PIN, RST_PIN); // Create MFRC522 instance

const int biepPin = 25;
int count = 0;

WiFiClientSecure client; // Create a global WiFiClientSecure instance

void setup() {
  Serial.begin(9600);
  WiFi.begin(ssid, password);
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nConnected to WiFi network with IP Address: ");
  Serial.println(WiFi.localIP());

  SPI.begin(); // Init SPI bus
  rfid.PCD_Init(); // Init MFRC522
  Serial.println("RFID reader initialized");
  pinMode(biepPin, OUTPUT);
}

void loop() {
  if(WiFi.status() == WL_CONNECTED){
    if (rfid.PICC_IsNewCardPresent() && rfid.PICC_ReadCardSerial()) {
      Serial.println("RFID tag detected");
      String uidString = "";
      for (byte i = 0; i < rfid.uid.size; i++) {
        uidString += String(rfid.uid.uidByte[i] < 0x10 ? "0" : "") + String(rfid.uid.uidByte[i], HEX);
      }
      uidString.toUpperCase();

      client.setInsecure(); // Set the client as insecure
      HTTPClient https;
      https.begin(client, serverName);
      https.addHeader("Content-Type", "application/x-www-form-urlencoded");
      
      String httpRequestData = "api_key=" + apiKeyValue + "&sensor=" + sensorName
                              + "&location=" + sensorLocation + "&value1=" + uidString;
      Serial.println("Sending HTTP request");
      int httpResponseCode = https.POST(httpRequestData);

      tone(biepPin, 1000);
      delay(100);
      noTone(biepPin);
      delay(50);
      // Second tone (lower frequency)
      tone(biepPin, 800);
      delay(100);
      noTone(biepPin);

      if (httpResponseCode > 0) {
        Serial.print("HTTP Response code: ");
        Serial.println(httpResponseCode);
      }
      else {
        Serial.print("Error code: ");
        Serial.println(httpResponseCode);
      }
      https.end();

      rfid.PICC_HaltA(); // Halt PICC
      rfid.PCD_StopCrypto1(); // Stop encryption on PCD
    }
  }
  else {
    Serial.println("WiFi Disconnected");
  }
  count = count++;
  Serial.println(count);
}

有没有大佬能帮我分析下，为什么闲置几小时后设备就无法读取标签了？可能是哪里的问题呢？

备注：内容来源于stack exchange，提问作者kucb