diff --git a/includes/discovery/os/watchguard.inc.php b/includes/discovery/os/watchguard.inc.php
index 972d2d98a9..05818f4de4 100644
--- a/includes/discovery/os/watchguard.inc.php
+++ b/includes/discovery/os/watchguard.inc.php
@@ -1,5 +1,5 @@
 <?php
 
-if (starts_with($sysDescr, array('WatchGuard', '1.3.6.1.4.1.3097.1.5'))) {
+if (starts_with('WatchGuard Fireware', $sysDescr) || starts_with('.1.3.6.1.4.1.3097.1.5', $sysObjectId)) {
     $os = 'firebox';
-}
+}
\ No newline at end of file
diff --git a/includes/discovery/os/windows.inc.php b/includes/discovery/os/windows.inc.php
index 8b25a46f91..3b4b066487 100644
--- a/includes/discovery/os/windows.inc.php
+++ b/includes/discovery/os/windows.inc.php
@@ -1,7 +1,9 @@
 <?php
 
-if (starts_with('1.3.6.1.4.1.311.1.1.3', $sysObjectId)) {
-    $os = 'windows';
-} elseif (str_contains('Windows', $sysDescr)) {
+if (starts_with('.1.3.6.1.4.1.311.1.1.3', $sysObjectId)) {
+    $os = 'windows';
+}
+
+if (str_contains($sysDescr, array('Windows'))) {
     $os = 'windows';
 }
diff --git a/includes/discovery/os/wxgoos.inc.php b/includes/discovery/os/wxgoos.inc.php
index fb6d13d189..b1ed3600c1 100644
--- a/includes/discovery/os/wxgoos.inc.php
+++ b/includes/discovery/os/wxgoos.inc.php
@@ -1,5 +1,9 @@
 <?php
 
-if (str_contains('NETOS 6.0', $sysDescr) && starts_with($sysObjectId, array('.1.3.6.1.4.1.901.1', '.1.3.6.1.4.1.17373'))) {
+if (str_contains('NETOS 6.0', $sysDescr)) {
     $os = 'wxgoos';
 }
+
+if (starts_with($sysObjectId, array('.1.3.6.1.4.1.901.1', '.1.3.6.1.4.1.17373'))) {
+    $os = 'wxgoos';
+}
\ No newline at end of file
diff --git a/includes/discovery/os/xirrus.inc.php b/includes/discovery/os/xirrus.inc.php
index 8a4e414d2f..c8249554f9 100644
--- a/includes/discovery/os/xirrus.inc.php
+++ b/includes/discovery/os/xirrus.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (str_contains('Xirrus', $sysDescr)) {
-    if (str_contains('ArrayOS', $sysDescr)) {
-        $os = 'xirrus_aos';
-    }
+if (str_contains($sysDescr, array('Xirrus', 'ArrayOS'))) {
+    $os = 'xirrus_aos';
 }
diff --git a/includes/discovery/os/zxr10.inc.php b/includes/discovery/os/zxr10.inc.php
index 272427bd29..420f93c055 100644
--- a/includes/discovery/os/zxr10.inc.php
+++ b/includes/discovery/os/zxr10.inc.php
@@ -1,7 +1,5 @@
 <?php
 
-if (starts_with('ZXR10', $sysDescr)) {
+if (str_contains($sysDescr, array('ZXR10', 'ZTE Ethernet Switch'))) {
     $os = 'zxr10';
-} elseif (str_contains('ZTE Ethernet Switch', $sysDescr)) {
-    $os = 'zxr10';
-}
+}
\ No newline at end of file
diff --git a/includes/discovery/os/zynos.inc.php b/includes/discovery/os/zynos.inc.php
index 9b4ded9707..8423797031 100644
--- a/includes/discovery/os/zynos.inc.php
+++ b/includes/discovery/os/zynos.inc.php
@@ -1,5 +1,5 @@
 <?php
 
-if (str_contains('.1.3.6.1.4.1.890', $sysObjectId) && (starts_with($sysDescr, array('EG', 'GS')))) {
+if (starts_with('.1.3.6.1.4.1.890', $sysObjectId) && starts_with($sysDescr, array('ES', 'GS'))) {
     $os = 'zynos';
 }
diff --git a/includes/discovery/os/zywall.inc.php b/includes/discovery/os/zywall.inc.php
index 08379b3498..bf7a66b3ff 100644
--- a/includes/discovery/os/zywall.inc.php
+++ b/includes/discovery/os/zywall.inc.php
@@ -1,7 +1,9 @@
 <?php
 
-if (str_contains('ZyWALL', $sysDescr)) {
-    $os = 'zywall';
-} elseif (starts_with('.1.3.6.1.4.1.890.1.15', $sysObjectId)) {
+if (starts_with('ZyWALL 2X', $sysDescr)) {
     $os = 'zywall';
 }
+
+if (strstr($sysObjectId, '.1.3.6.1.4.1.890.1.15')) {
+    $os = 'zywall';
+}
\ No newline at end of file