Arduino only writes(?) 1 card and doesn't recognize others

Hi! I have been adding cards to the arduino (I tap them then it says “successfully added”) but when I tap them after to test if they really are added it says access denied to the system (only the 1st I added to the system is successful in the process - meaning only 1 card does have an access to the system). What seems to be the problem for this Gentlemen? I get this code to this website and I’m just following instructions from his site (I’ve added some modifications to his project tho). The code is attached below. Thank you for your answers!

Tap_Card.ino (14.7 KB)

  client.println("POST /insert_mysql.php HTTP/1.1");  // insert the link to the database

In setup(), you don't HAVE a client instance, so POSTing to a non-existent instance is silly.

  do {
    successRead = getID();              // sets successRead to 1 when we get read from reader otherwise 0
    if (programMode) {                  // Program Mode cycles through RGB waiting to read a new card (optional)
    } else {
  while (!successRead);                 //the program will not go further while you not get a successful read

Why the hell do you bother testing programMode, when you do nothing if it is true and nothing if it isn't true?

You CLEARLY need more Serial.print() statements in the code, to see what it is actually doing. What mode are you in? How many cards are stored in EEPROM when you scan each card?