SQL query fails in prod environment on IIS but works in test environment running Apache

Question

I'm having a bit of an issue with quires failing when I upload to the live environment while they are fully functional in the test environment, I'm at a loss at this point about where the error may be so I finally broke down and decided to ask those of stack overflow that may be much more skilled than myself if there's something I've missed. The quires look at serial number information from two different tables to pull system specs and any hard drive information associated with the parent serial

<?php
$Dev_HDD = 0;

$con=mysqli_connect("localhost","username","user_password","database");
// Check connection
if (mysqli_connect_errno())
    {
        echo "Failed to connect to MySQL: " . mysqli_connect_error();
    }

if (isset($_POST["serial"]))

{
    $SerialNumber = $_POST["serial"];

    $sql ="SELECT system.Manufacturer, system.Model, system.SerialNumber, system.Processor, system.Memory FROM system  WHERE SerialNumber = '" .$SerialNumber. "'" ;

    if ($result=mysqli_query($con,$sql))
    {


        // Fetch one and one row
        while ($row=mysqli_fetch_row($result))
        {
            $System_Manufacturer = $row[0];
            $System_Model = $row[1];
            $System_SerialNumber = $row[2];
            $System_Processor = $row[3];
            $System_Memory = $row[4];


?>

    <table border="0" height="100%" width="100%" align="left" valign="top">
        <tr>
            <td colspan="2">
                <hr />
            </td>
        </tr>

        <tr>
            <td colspan="2" valign="top">System Summary:</td>
        </tr>
        <tr>
            <td colspan="2">
                <hr />
            </td>
        </tr>

        <tr>
            <td>System Manufacturer</td>
            <td>
                <?php echo $System_Manufacturer; ?>
            </td>
        </tr>

        <tr>
            <td>System Model:</td>
            <td>
                <?php echo $System_Model; ?>
            </td>
        </tr>

        <tr>
            <td valign="top">System Serial Number</td>
            <td valign="top">
                <?php echo $System_SerialNumber; ?>
            </td>
        </tr>

        <tr>
            <td valign="top">System Processor</td>
            <td valign="top">
                <?php echo $System_Processor; ?>
            </td>
        </tr>

        <tr>
            <td valign="top">System Memory</td>
            <td valign="top">
                <?php echo $System_Memory; ?>
            </td>
        </tr>

    <?php
}

        // Free result set
        mysqli_free_result($result);
    }
    else
    {
        echo "The serial number specified could not be located<br>";
    }

    $sql ="SELECT device.recid, device.Manufacturer, device.Model, device.SerialNumber, device.Capacity, device.RPM, device.ErasureMethod, device.ErasureResults FROM device WHERE SystemSerialNumber = '" . $System_SerialNumber . "'" ;

    if ($result=mysqli_query($con,$sql))
    {


        // Fetch one and one row
        while ($row=mysqli_fetch_row($result))
        {
            $Dev_Recid = $row[0];
            $Dev_Manufacturer = $row[1];
            $Dev_Model = $row[2];
            $Dev_DeviceSerialNumber = $row[3];
            $Dev_Capacity = $row[4];
            $Dev_RPM = $row[5];
            $Dev_ErasureMethod = $row[6];
            $Dev_ErasureResults = $row[7];

    ?>

    <tr>
        <td colspan="2">
            <hr />
        </td>
    </tr>

    <tr>
        <td colspan="2" valign="top">Storage Summary(<?php echo $Dev_HDD = $Dev_HDD + 1; ?>):</td>
    </tr>

    <tr>
        <td colspan="2">
            <hr />
        </td>
    </tr>

    <tr>
        <td>Hard Drive Manufacturer</td>
        <td>
            <?php echo $Dev_Manufacturer; ?>
        </td>
    </tr>

    <tr>
        <td>Hard Drive Model:</td>
        <td>
            <?php echo $Dev_Model; ?>
        </td>
    </tr>

    <tr>
        <td valign="top">Serial Number Lookup</td>
        <td valign="top">
            <?php echo $Dev_DeviceSerialNumber; ?>
        </td>
    </tr>

    <tr>
        <td valign="top">Hard Drive  Capacity</td>
        <td valign="top">
            <?php echo $Dev_Capacity; ?>
        </td>
    </tr>

    <tr>
        <td valign="top">Hard Drive  Speed</td>
        <td valign="top">
            <?php echo $Dev_RPM; ?>
        </td>
    </tr>

    <tr>
        <td>Erasure Method:</td>
        <td>
            <?php echo $Dev_ErasureMethod; ?>
        </td>
    </tr>

    <tr>
        <td>Erasure Results:</td>
        <td>
            <?php echo $Dev_ErasureResults; ?>
        </td>
    </tr>

    <tr>
        <td>Parent Serial Number:</td>
        <td>
        <?php echo "<a href='logs/" .$Dev_DeviceSerialNumber.".log' target='_blank'>".$Dev_DeviceSerialNumber."</a> <br>";?>
        </td>
    </tr>
</table>

<?php
        }
    }

        // Free result set
        mysqli_free_result($result);


    mysqli_close($con);
}
?>



<?php

        echo " <br>";

        echo "<pre></pre>";
?>