fix: 10-wan script

opnsense/10-wan

@@ -14,7 +14,6 @@ require_once("system.inc");
 // Read CARP event arguments
 $subsystem = !empty($argv[1]) ? $argv[1] : '';
 $type = !empty($argv[2]) ? $argv[2] : '';
-$primary_vhid = '1';
 
 // Accept only MASTER/BACKUP events
 if (!in_array($type, ['MASTER', 'BACKUP'])) {
@@ -29,7 +28,10 @@ if (!preg_match('/^[a-z0-9_]+@\S+$/i', $subsystem)) {
 }
 
 // Only react to the primary VHID
-if (!preg_match('/@' . preg_quote($primary_vhid, '/') . '$/', $subsystem)) {
+list($vhid, $iface) = explode('@', $subsystem);
+$primary_vhid = '1'; //
+
+if ($vhid !== $primary_vhid) {
     exit(0); // ignore events from other VHIDs
 }