Trying to display sensor data correctly on Thingspeak

Hello,

I can upload the following code without errors to my ESP32 device to which pin14 there is a three-pinned DHT11 sensor connected from its middle pin, as well as to 3V3 by its left pin and to GND by its right pin (looked while facing the blue sensor side).

After uploading the following code, I get the DHT11 sensor data to read on the serial monitor updating every 20 second. However, the values never update to Thingspeak. Instead, I get only random numbers between 0 and 100 to display on the graphs of my Thingspeak channel.

Here is the code I have on the Arduino editor:

#include "DHT.h"
#include <WiFi.h>
#include "secrets.h"
#include "ThingSpeak.h"


#define DHTPIN 14    

#define DHTTYPE DHT11

const char* ssid = "1248924";   // your network SSID (name) 
const char* password = "48FHSL42GYE";   // your network password

WiFiClient  client;

unsigned long myChannelNumber = 1;
const char * myWriteAPIKey = "NW34FGOB290GRL2";

// Timer variables 
unsigned long lastTime = 0;
unsigned long timerDelay = 10000;

DHT dht(DHTPIN, DHTTYPE);

// Initialize our values
float h = dht.readHumidity();
float t = dht.readTemperature();
float f = dht.readTemperature(true);
String myStatus = "";

void setup() {
  Serial.begin(115200);
  Serial.println(F("DHT11 test!"));

  dht.begin();

  WiFi.mode(WIFI_STA);   
 
 ThingSpeak.begin(client);
}

void loop() {
  
  delay(20000);

 
  float h = dht.readHumidity();
  
  float t = dht.readTemperature();
  
  float f = dht.readTemperature(true);


  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }

  if(WiFi.status() != WL_CONNECTED){      
    Serial.print("Attempting to connect");
    while(WiFi.status() != WL_CONNECTED){
      WiFi.begin(ssid, password); 
      delay(5000);     
    } 
    Serial.println("\nConnected.");
  }



  float hif = dht.computeHeatIndex(f, h);

  float hic = dht.computeHeatIndex(t, h, false);

  Serial.print(F("Humidity: "));
  Serial.print(h);
  Serial.print(F("%  Temperature: "));
  Serial.print(t);
  Serial.print(F("°C "));
  Serial.print(f);
  Serial.print(F("°F  Heat index: "));
  Serial.print(hic);
  Serial.print(F("°C "));
  Serial.print(hif);
  Serial.println(F("°F"));

int x = ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);

if(x == 200){
  Serial.println("Channel update successful.");
}
else{
  Serial.println("Problem updating channel. HTTP error code " + String(x));
}
}

This is what my serial monitor displays:

Problem updating channel. HTTP error code -210
Humidity: 61.00%  Temperature: 23.30°C 73.94°F  Heat index: 23.28°C 73.90°F
Problem updating channel. HTTP error code -210
Humidity: 61.00%  Temperature: 23.30°C 73.94°F  Heat index: 23.28°C 73.90°F
Problem updating channel. HTTP error code -210
Humidity: 60.00%  Temperature: 23.40°C 74.12°F  Heat index: 23.36°C 74.05°F
Problem updating channel. HTTP error code -210
(the list goes on...)

Possible clues:
I checked that the Write API key is ok. Since I have two channels altogether at Thingspeak, I suspect that I need to enter myChannelNumber as 1 or 2. I guess, based on the order that they display on the My channels page. But I checked them both and no difference.. Also I have secrets.h in a folder "secrets" under Arduino/libraries. I put there all my data as well. Interestingly, the program never asked for secrets.h data though - I just included it based on routine.

Thanks for any advice!