Project Euler - 3 | why program doesn't t exit from the while loop?

Hello I'm Andrea and I'm a beginner to programming,

I' m trying to solve the Project Euler - problem 3, but I can't understand why the "j" doesn't exit from the while loop ( It generates an infinite loop ).

When the "j" enters in the else (inside the while) the "$prime" variable value is set to true, so I suppose the program has to exit from the while loop (because the second condition: while ( $j < $i || $prime != true || $noPrime != true )), but the program continues to go on.

I know the code is not complete for the problem and not beautiful too, but I'm really stuck on this problem.

Code below:

<body>
    
<?php
$num = 20;
$z = 0; $j = 2;

$fPrimes = [];

$prime = false;
$noPrime = false;
$primeFactor = 0;

for ($i=2; $i < 20; $i++) { //check for every number under the $num

    echo "<b>My i : " . $i . "</b><br>";

    if ($num % $i == 0) { //check if is a divisor

        $j = 2;
        if ($i == 2)  $j = 1;
       
        while ( $j < $i || $prime != true || $noPrime != true ) { 

            echo "My j : " . $j . "<br>";

            if ($i % $j != 0) { // j is not a divisor

                echo "My j : " . $j . " not a divisor<br>";

            }elseif ($i % $j == 0 && $j != $i && $j != 1) { // j = divisor but not =$i and not =1

                echo $i . " Not f.prime!<br>";

                $noPrime = true;
            }else{ // j is a divisor and prime factor

                echo $i . " It's a f.prime!<br><br>";
                $primeFactor [$z] = $i;

                $prime = true;
                $z++ ;
            }
            if ($prime == false && $noPrime == false) $j++;    
        }

        $prime =  false;  
        $noPrime =  false;
        
    }else echo "<br>" . $i . " Not divisor.</br><br>";
}

for ($i=0; $i < count($primeFactor ) ; $i++)  echo $primeFactor [$i] . " ";

?>

</body>

Here below the result:

My i : 2
My j : 1
2 It's a f.prime!

My j : 1
2 It's a f.prime!

.. infinite loop

My j : 1
2 It's a f.prime!

Thanks in advance for the help