Communication between Postman and Arduino

Question

I plan to send from a server a POST request to my Arduino Uno WiFi Rev2. More correctly, when the server sends this request a servomotor controlled by the Arduino should start moving. Right now, I'm using Postman to try and connect with the Arduino but I can't get it to work. So first I connect the Arduino to WiFi using my smartphone as a hotspot. This should be the unit's IP address, right?

I then try to send a POST request to this IP but it doesn't work. I'm also unsure which port number I should use, so I have just been trying with the standard ones (80, 4430, etc).

What am I doing wrong and how should I proceed?

EDIT: Here is my code.

#include <SPI.h>
#include <Servo.h>
#include <WiFiNINA.h>


char ssid[]       = "MyNetwork";  // The network SSID
char pass[]       = "testtest"; // The network password

int status        = WL_IDLE_STATUS; // The Wifi radio's connection status
Servo servo_9; // Initializes the servomotor

WiFiServer server(80); // Server socket
//WiFiClient client;
WiFiClient client = server.available();


void setup() {
  // Connects the servomotor to pin 9
  servo_9.attach(9, 500, 2500);
  
  // Initialize serial and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // Wait for serial port to connect. Needed for native USB port only
  }

  enable_WiFi();
  connect_WiFi();

  server.begin();
  printCurrentNet();
  printWifiData();
}


void loop() {
  // Check the network connection once every 10 seconds:
  delay(10000);

  client = server.available();
  if(client){
    printWEB();
  }
}


void enable_WiFi(){
   // Check for the WiFi module:
  if (WiFi.status() == WL_NO_MODULE) {
    Serial.println("Communication with WiFi module failed!");
    // Don't continue
    while (true);
  }

  // Check if the latest Firmware version is installed
  String fv = WiFi.firmwareVersion();
  if (fv < WIFI_FIRMWARE_LATEST_VERSION) {
    Serial.println("Please upgrade the firmware");
  }
}


void connect_WiFi(){
  // Attempt to connect to Wifi network:
  while (status != WL_CONNECTED) {
    Serial.print("Attempting to connect to WPA SSID: ");
    Serial.println(ssid);
    // Connect to WPA/WPA2 network:
    status = WiFi.begin(ssid, pass);
    // Wait 10 seconds for connection:
    delay(10000);
  }

  // Now the arduino is connected, so print out the data:
  Serial.print("You're connected to the network: ");
  Serial.println();  
}


void printCurrentNet() {
  // Print the SSID of the network you're attached to:
  Serial.print("SSID: ");
  Serial.println(WiFi.SSID());

  // Print the MAC address of the router you're attached to:
  byte bssid[6];
  WiFi.BSSID(bssid);
  Serial.print("BSSID: ");
  printMacAddress(bssid);

  // Print the received signal strength:
  long rssi = WiFi.RSSI();
  Serial.print("Signal strength (RSSI): ");
  Serial.println(rssi);

  // Print the encryption type:
  byte encryption = WiFi.encryptionType();
  Serial.print("Encryption Type: ");
  Serial.println(encryption, HEX);
  Serial.println();
}


void printWifiData() {
  Serial.println("Your board's IP and MAC address: ");
  // Print your board's IP address:
  IPAddress ip = WiFi.localIP();
  Serial.print("IP Address: ");
  Serial.println(ip);

  // Print your MAC address:
  byte mac[6];
  WiFi.macAddress(mac);
  Serial.print("MAC address: ");
  printMacAddress(mac);
  Serial.println();
}


// Find the MAC adress for your Arduino board
void printMacAddress(byte mac[]) {
  for (int i = 5; i >= 0; i--) {
    if (mac[i] < 16) {
      Serial.print("0");
    }
    Serial.print(mac[i], HEX);
    if (i > 0) {
      Serial.print(":");
    }
  }
  Serial.println();
}


void printWEB() {

  if (client) {                             // if you get a client,
    Serial.println("new client");           // print a message out the serial port
    String currentLine = "";                // make a String to hold incoming data from the client
    while (client.connected()) {            // loop while the client's connected
      if (client.available()) {             // if there's bytes to read from the client,
        char c = client.read();             // read a byte, then
        Serial.write(c);                    // print it out the serial monitor
        if (c == '\n') {                    // if the byte is a newline character

          // if the current line is blank, you got two newline characters in a row.
          // that's the end of the client HTTP request, so send a response:
          if (currentLine.length() == 0) {

            // HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
            // and a content-type so the client knows what's coming, then a blank line:
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println();

            // The HTTP response ends with another blank line:
            client.println();
            // break out of the while loop:
            break;
          }
          else {      // if you got a newline, then clear currentLine:
            currentLine = "";
          }
        }
        else if (c != '\r') {    // if you got anything else but a carriage return character,
          currentLine += c;      // add it to the end of the currentLine
        }
      }
    }
    // close the connection:
    client.stop();
    Serial.println("client disconnected");
  }
}


void servomotorGate(){
  int position = 0;
  for (position = 0; position <= 90; position += 1) {
    servo_9.write(position);
    Serial.println("Opening the gate");
  }
  delay(5000); // Wait for 5000 millisecond(s)
  for (position = 90; position >= 0; position -= 1) {
    servo_9.write(position);
    Serial.println("Closing the gate");
  }
}

Answer 1

I added the server client to listen for connections. However, the main reason why I couldn't connect to my IP address with Postman was that I was trying to get WiFi from my phone as a hotspot. I guess there is a problem with the port forwarding when using a hotspot. In the end, I solved the issue by connecting to a normal router WiFi network.