POST request using a nodeMCU arduino board is not successfull

Question

Other similar questions appear to be for older boards using slightly different code. I'm also very new to playing around with ESP8266 boards, so I might be missunderstanding tutorials and what the functions do.

I am trying to send data from and nodemcu board using a post request, my code is as follows:

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>

//SSID and Password of your WiFi router
const char* ssid = "MYSSID";  // Enter SSID here
const char* password = "MYPASSWORD";  //Enter Password here

const char *URL = "MYDOMAINNAME.com/endpoint.php";

WiFiClient client;
HTTPClient httpClient;

const int trigPin = 12;
const int echoPin = 14;

//define sound velocity in cm/uS
#define SOUND_VELOCITY 0.034


long duration;
float distanceCm;
float distanceInch;

void setup() {
  Serial.begin(115200); // Starts the serial communication
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input

  WiFi.begin(ssid, password);
  Serial.println("Connecting to WIFI…");
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
 

}
  


void loop() {
  // Clears the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate the distance
  distanceCm = duration * SOUND_VELOCITY/2;
  

   delay(1000);
  // Prints the distance on the Serial Monitor
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);


    String data = "data="+String(distanceCm);
 
    httpClient.begin(client,URL);
    httpClient.addHeader("Content-Type", "application/x-www-form-urlencoded");
    httpClient.POST(data);
    String content = httpClient.getString();
    httpClient.end();
 
    Serial.println(content);


  
  delay(1000);
}

On the server side, I have a very simple php script that I'm using for debugging at the moment:

<?php

$field1=$_POST["data"];
$myfile = fopen($field1.".txt", "w") or die("Unable to open file!");
fclose($myfile);

echo $field1;

Simply I'm using this to see if the post request is a success, if it is then a txt file will be generated.

I've tried various combinations or the const char *URL, either starting my domain with https://, https://wwww, www, http://, http://www. All fail to give a result, the only one that gives something interesting or of note in the serial monitor is http://www. which returns a 301 error, all other combinations print nothing into the serial monitor.

I'm hosting my endpoint on a shared server (Namecheap) with no htaccess rules set up (just as is).