Reading a website and selecting imformation among the code return

You have to add a null terminator to your buffer before you convert it to a String.

You also have to make sure you don't over-fill the buffer.

String readPage() {
  //read the page, and capture & return everything between '<' and '>'

  stringPos = 0;
  memset( &inString, 0, 32 ); //clear inString memory

  while(true){

    if (client.available()) {
      char c = client.read();

      switch (c) {
        
      case '<':
        stringPos = 0;
        startRead = true; //Ready to start reading the part 
        break;

      case '>':
        if (startRead) {
          inString[stringPos++] = '\0'; // Add null terminator
          client.stop();
          client.flush();
          Serial.println("disconnecting.");
          return inString;
        }

      default:
        if (startRead && stringPos < (sizeof instring - 1)) {
          inString[stringPos++] = c;
        }
      }
    }
  }
}