Error: A connection with the server could not be established

<meta http-equiv="Content-Type" content="text/html;charset=TIS-620" lang="th">
<meta name="viewport" content="width=device-width, initial-scale=1" />
<font face="MS Sans Serif, Default Font" size="1">


<div id="fb-root"></div>
<script async defer crossorigin="anonymous" src="https://connect.facebook.net/th_TH/sdk.js#xfbml=1&version=v3.3&appId=1733965693288154&autoLogAppEvents=1"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js"></script>


<script language="JavaScript" type="text/javascript">
$(document).ready(function(){
  $('[data-toggle="tooltip"]').tooltip();   
});
</script>




<script language="JavaScript" type="text/javascript">
document.cookie = "screen_w=" + screen.availWidth ;
document.cookie = "screen_h=" + screen.availHeight;
</script>




<script language="JavaScript" type="text/javascript">
<!--
function validateForm() {
    var x = document.forms["myForm"]["name"].value;
    if (x == "") {
        alert("Name must be filled out");
        return false;
    }
		 if (!/^[a-zA-Z]*$/g.test(x)) {
        alert("Invalid characters");

        return false;
    }
}
//-->
</script>

<!-- check file size befor upload -->

<script language="JavaScript">

function showFileSize() {
    var input, file;

    // (Can't use `typeof FileReader === "function"` because apparently
    // it comes back as "object" on some browsers. So just see if it's there
    // at all.)
    if (!window.FileReader) {
        bodyAppend("p", "The file API isn't supported on this browser yet.");
        return;
    }

    input = document.getElementById('fileinput');
    if (!input) {
        document.getElementById("myForm").submit();
    }
    else if (!input.files) {
        document.getElementById("myForm").submit();
    }
    else if (!input.files[0]) {
        document.getElementById("myForm").submit();
    }
    else {
        file = input.files[0];
        bodyAppend("p", "File " + file.name + " is " + file.size + " bytes in size");
				if(file.size < 20000000000)
				{
				     document.getElementById("myForm").submit();
				}else
				{
			 		 window.alert( "ขนาดของไฟล์ต้องไม่เกิน 20000000000 bytes ( 20000000 KB)"+"\n------------------------\nFile " + file.name + " มีขนาด " + file.size + " bytes ("+Math.round(file.size/1024)+"KB)" );
				}
    }
}

function bodyAppend(tagName, innerHTML) {
    var elm;

    elm = document.createElement(tagName);
    elm.innerHTML = innerHTML;
    document.body.appendChild(elm);
}
</script>

<!-- end check file size befor upload -->	
	
			<table border=0  bgcolor="" width= cellpadding="0" cellspacing="0">	

			<form action="teacher.asp?work=2" method="post">							
			 			 			 			 	
			<tr><td align="right" bgcolor=""><font class="title"><b>รหัสวิชา <img src="skin1\arrow.gif"></td><td>&nbsp; 008</td></tr>
			<tr><td align="right" bgcolor=""><font class="title"><b>ชื่อวิชา <img src="skin1\arrow.gif"> </td><td>&nbsp; New age </td></tr>
			<tr><td align="right"  bgcolor=""><font class="title"><b>หน่วยกิต <img src="skin1\arrow.gif"> </td><td>&nbsp; 2</td></tr>
			<tr><td align="right" width="20%" bgcolor=""><font class="title"><b>ภาคเรียนที่ <img src="skin1\arrow.gif"> </td><td>&nbsp;1/ 2556</td></tr>
			<tr><td align="right" valign="top"  bgcolor=""><font class="title"><b>คำอธิบายวิชา <img src="skin1\arrow.gif"> </td><td>&nbsp;<div></td></tr>
			<tr><td align="right" valign="top"  bgcolor=""><font class="title"><b>แผนการสอน <img src="skin1\arrow.gif"> </td><td>&nbsp; </td></tr>
			<tr><td align="right" valign="top"  bgcolor=""><font class="title"><b>รายละเอียดอื่นๆ<img src="skin1\arrow.gif"> </td><td>&nbsp;</td></tr>
			<tr><td align="right" valign="top"  bgcolor=""><font class="title"><b>เกณฑ์การตัดเกรด <img src="skin1\arrow.gif"> </td>
			<td><table border="0">
			<tr><td><b>A <td><img src="skin1\to.gif"></td></td><td>80</tr>
			<tr><td><b>B+<td><img src="skin1\to.gif"></td></td><td>75</tr>
			<tr><td><b>B <td><img src="skin1\to.gif"></td></td><td>70</tr>
			<tr><td><b>C+ <td><img src="skin1\to.gif"></td></td><td>65</tr>
			<tr><td><b>C <td><img src="skin1\to.gif"></td></td><td>60</tr>
			<tr><td><b>D+ <td><img src="skin1\to.gif"></td></td><td>57</tr>
			<tr><td><b>D <td><img src="skin1\to.gif"></td></td><td>50</tr>
			<tr><td><b>F <td><img src="skin1\to.gif"></td></td><td>0</tr>							
			</table>																															
			
			</td></tr>
			</form>
			</table>