<?php
$servername = "localhost";
$username = "test";
$password = "alltest123";
$dbname = "test";

// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

// Get values from form
$ixname=($_POST['ixp']);
$peername=($_POST['test2']);
$asname=($_POST['asname']);
$ipv4=($_POST['ipv4']);
$ipv6=($_POST['ipv6']);
$descr=($_POST['test3']);
$node=($_POST['node']);
$category=($_POST['category']);

$sql = "INSERT INTO tbl_peer (ixname, peername, asname, ipv4, ipv6, descr, node, category)
VALUES ('$ixp', '$test2', '$asname', '$ipv4', '$ipv6', '$test3', '$node', '$category')";

if (mysqli_query($conn, $sql)) {
    echo "New record created successfully";
} else {
    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
}

<table width="300" border="0" align="center" cellpadding="0" cellspacing="1">
<tr>
<td><form name="form1" method="post" action="insert_ac.php">
<table width="100%" border="0" cellspacing="1" cellpadding="3">
<tr>
<td colspan="3"><strong>Test Form </strong></td>
</tr>
<tr>
<td width="71">IX Name</td>
<td width="6">:</td>
<td width="301"><input name="ixp" type="text" id="ixp"></td>
</tr>
<tr>
<td>Peer Name</td>
<td>:</td>
<td><input name="test2" type="text" id="test2"></td>
</tr>
<tr>
<td>ASN</td>
<td>:</td>
<td><input name="asname" type="text" id="asname"></td>
</tr>
<tr>
<td>Ipv4 Address</td>
<td>:</td>
<td><input name="ipv4" type="text" id="ipv4"></td>
</tr>
<tr>
<td>Ipv6 Address</td>
<td>:</td>
<td><input name="ipv6" type="text" id="ipv6"></td>
</tr>
<tr>
<td>Description</td>
<td>:</td>
<td><input name="test3" type="text" id="test3"></td>
</tr>
<tr>
<td>Node</td>
<td>:</td>
<td><input name="node" type="text" id="node"></td>
</tr>
<tr>
<td>Category</td>
<td>:</td>
<td><input name="category" type="text" id="category"></td>
</tr>
<tr>
<td colspan="3" align="center"><input type="submit" name="Submit" value="Submit"></td>
</tr>
</table>
</form>
</td>
</tr>
</table>

PHP 7.0.33-0+deb9u1 (cli) (built: Dec  7 2018 11:36:49) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
    with Zend OPcache v7.0.33-0+deb9u1, Copyright (c) 1999-2017, by Zend Technologies
    with Xdebug v2.5.0, Copyright (c) 2002-2016, by Derick Rethans

mysql  Ver 15.1 Distrib 10.1.37-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2

PHP Notice:  Undefined variable: ixp in /var/www/insert_ac.php on line 25, referer: testb.php
PHP Stack trace:, referer:testb.php
PHP   1. {main}() /var/www/insert_ac.php:0, referer: testb.php
PHP Notice:  Undefined variable: test2 in /var/www/insert_ac.php on line 25, referer: testb.php
PHP Stack trace:, referer: testb.php
PHP   1. {main}() /var/www/insert_ac.php:0, referer: testb.php
PHP Notice:  Undefined variable: test3 in /var/www/insert_ac.php on line 25, referer:testb.php
PHP Stack trace:, referer: testb.php
PHP   1. {main}() /var/www/insert_ac.php:0, referer: testb.php