diff --git a/encoder/network.php b/encoder/network.php
index 08d1c1c..f695890 100755
--- a/encoder/network.php
+++ b/encoder/network.php
@@ -1,7 +1,8 @@
+<?php include 'header.php'; ?>
 <?php
-// network-form-handler.php
+
 $jsonFile = __DIR__ . '/network.json';
-$iface = trim(shell_exec("ip route get 1.1.1.1 | awk '{print $5; exit}'"));
+$iface = find_first_physical_ethernet();
 
 $defaults = [
     'primary' => [
@@ -34,8 +35,6 @@ $defaults = [
         'network_secondary_ipv6_dns1' => '',
         'network_secondary_ipv6_dns2' => '',
     ],
-    'firewall' => 'disable',
-    'ips' => ['', '', '', '', '']
 ];
 
 if (file_exists($jsonFile)) {
@@ -152,8 +151,6 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
                 'network_secondary_ipv6_dns1' => $secondary_vlan,
                 'network_secondary_ipv6_dns2' => $secondary_vlan
             ],
-            'firewall' => 'disable',
-            'ips' => ['', '', '', '', '']
         ];
         $json = json_encode($new, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
         if (file_put_contents($jsonFile, $json, LOCK_EX) === false) {
@@ -161,14 +158,134 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
         } else {
             $data = $new;
             $success = 'Saved.';
-        }
 
-        update_network();
+            $netplan = [
+                'network' => [
+                    'version'  => 2,
+                    'renderer' => 'networkd',
+                    'ethernets' => [
+                        $iface => []
+                    ],
+                    'vlans'    => []
+                ]
+            ];
+
+            /* ---------- helper to build IPv4/IPv6 ---------- */
+            function build_interface(array $d, string $key): array
+            {
+                $cfg = [];
+
+                /* IPv4 */
+                switch ($d['mode']) {
+                    case 'dhcp':
+                        $cfg['dhcp4'] = true;
+                        break;
+
+                    case 'static':
+                        if (!empty($d["network_{$key}_ip"]) && !empty($d["network_{$key}_subnet"])) {
+                            $cfg['addresses'][] =
+                                $d["network_{$key}_ip"] . '/' . $d["network_{$key}_subnet"];
+                        }
+                        if (!empty($d["network_{$key}_gateway"])) {
+                            $cfg['routes'][] = [
+                                'to'  => 'default',
+                                'via' => $d["network_{$key}_gateway"]
+                            ];
+                        }
+                        break;
+
+                    case 'disabled':
+                        $cfg['dhcp4'] = false;
+                        break;
+                }
+
+                /* IPv6 */
+                switch ($d['modev6']) {
+                    case 'auto': // SLAAC
+                        $cfg['accept-ra'] = true;
+                        $cfg['dhcp6'] = false;
+                        break;
+
+                    case 'dhcp6':
+                        $cfg['dhcp6'] = true;
+                        $cfg['accept-ra'] = false;
+                        break;
+
+                    case 'static':
+                        if (!empty($d["network_{$key}_ipv6"]) && !empty($d["network_{$key}_ipv6_prefix"])) {
+                            $cfg['addresses'][] =
+                                $d["network_{$key}_ipv6"] . '/' . $d["network_{$key}_ipv6_prefix"];
+                        }
+                        if (!empty($d["network_{$key}_ipv6_gateway"])) {
+                            $cfg['routes'][] = [
+                                'to'  => '::/0',
+                                'via' => $d["network_{$key}_ipv6_gateway"]
+                            ];
+                        }
+                        $cfg['accept-ra'] = false;
+                        break;
+
+                    case 'disabled':
+                        $cfg['dhcp6'] = false;
+                        $cfg['accept-ra'] = false;
+                        break;
+                }
+
+                /* DNS */
+                $dns = array_filter([
+                    $d["network_{$key}_dns1"] ?? '',
+                    $d["network_{$key}_dns2"] ?? '',
+                    $d["network_{$key}_ipv6_dns1"] ?? '',
+                    $d["network_{$key}_ipv6_dns2"] ?? ''
+                ]);
+
+                if ($dns) {
+                    $cfg['nameservers']['addresses'] = array_values($dns);
+                }
+
+                return $cfg;
+            }
+
+            /* ---------- VLAN detection ---------- */
+            $primary_vlan   = trim($data['primary']['network_primary_vlan'] ?? '');
+            $secondary_vlan = trim($data['secondary']['network_secondary_vlan'] ?? '');
+
+            $uses_vlan = ($primary_vlan !== '' || $secondary_vlan !== '');
+
+            /* ---------- No VLAN: apply primary only ---------- */
+            if (!$uses_vlan) {
+                $netplan['network']['ethernets'][$iface] =
+                    build_interface($data['primary'], 'primary');
+            }
+            /* ---------- VLAN mode ---------- */ else {
+                // base iface must exist but empty
+                $netplan['network']['ethernets'][$iface] = [];
+
+                if ($primary_vlan !== '') {
+                    $vif = "{$iface}.{$primary_vlan}";
+                    $netplan['network']['vlans'][$vif] = array_merge([
+                        'id'   => (int)$primary_vlan,
+                        'link' => $iface
+                    ], build_interface($data['primary'], 'primary'));
+                }
+
+                if ($secondary_vlan !== '') {
+                    $vif = "{$iface}.{$secondary_vlan}";
+                    $netplan['network']['vlans'][$vif] = array_merge([
+                        'id'   => (int)$secondary_vlan,
+                        'link' => $iface
+                    ], build_interface($data['secondary'], 'secondary'));
+                }
+            }
+
+            /* ---------- write ---------- */
+            $yaml = netplan_yaml($netplan);
+            file_put_contents('/var/www/50-cloud-init.yaml', $yaml);
+        }
     }
 }
 ?>
 
-<?php include 'header.php'; ?>
 <form method="POST" novalidate>
     <div class="containerindex">
         <div class="grid">
diff --git a/encoder/static.php b/encoder/static.php
index 15feac7..e68cd90 100755
--- a/encoder/static.php
+++ b/encoder/static.php
@@ -40,6 +40,71 @@ function deleteDir(string $dir): void
     rmdir($dir);
 }
 
+function find_first_physical_ethernet(): ?string
+{
+    foreach (scandir('/sys/class/net') as $iface) {
+        if ($iface === '.' || $iface === '..' || $iface === 'lo') {
+            continue;
+        }
+
+        $net = "/sys/class/net/$iface";
+
+        if (!is_link("$net/device")) {
+            continue;
+        }
+
+        $type = @trim(file_get_contents("$net/type"));
+        if ($type !== '1') {
+            continue;
+        }
+
+        if (is_dir("$net/wireless")) {
+            continue;
+        }
+
+        if (is_dir("$net/bridge")) {
+            continue;
+        }
+
+        $addrAssignType = @trim(file_get_contents("$net/addr_assign_type"));
+        if ($addrAssignType !== '0') {
+            continue;
+        }
+        return $iface;
+    }
+    return null;
+}
+
+function netplan_yaml(array $data, int $indent = 0): string
+{
+    $yaml = '';
+    $pad  = str_repeat('  ', $indent);
+
+    foreach ($data as $key => $value) {
+        if (is_array($value)) {
+            $is_list = array_keys($value) === range(0, count($value) - 1);
+
+            if ($is_list) {
+                foreach ($value as $item) {
+                    if (is_array($item)) {
+                        $yaml .= "{$pad}-\n" . netplan_yaml($item, $indent + 1);
+                    } else {
+                        $yaml .= "{$pad}- {$item}\n";
+                    }
+                }
+            } else {
+                $yaml .= "{$pad}{$key}:\n" . netplan_yaml($value, $indent + 1);
+            }
+        } else {
+            if (is_bool($value)) {
+                $value = $value ? 'true' : 'false';
+            }
+            $yaml .= "{$pad}{$key}: {$value}\n";
+        }
+    }
+
+    return $yaml;
+}
 
 function update_service($which_service)
 {