diff --git a/front/js/ui_components.js b/front/js/ui_components.js
index 73119e97..98186728 100755
--- a/front/js/ui_components.js
+++ b/front/js/ui_components.js
@@ -144,7 +144,7 @@ function validateRegex(elem) {
       } else {
           iconSpan.html("<i class='fa fa-xmark'></i>");
           showModalOk('WARNING', getString("Gen_Invalid_Value"));
-          inputElem.attr("data-is-valid", "0"); 
+          inputElem.attr("data-is-valid", "0");
       }
   }
 
@@ -450,10 +450,10 @@ function addOptionFromModalInput() {
 
 
 // --------------------------------------------------------
-// Generate a random MAC address starting 00:1A
+// Generate a random MAC address starting FA:CE
 function generate_NEWDEV_devMac() {
   const randomHexPair = () => Math.floor(Math.random() * 256).toString(16).padStart(2, '0').toUpperCase();
-  $('#NEWDEV_devMac').val(`00:1A:${randomHexPair()}:${randomHexPair()}:${randomHexPair()}:${randomHexPair()}`.toLowerCase());
+  $('#NEWDEV_devMac').val(`FA:CE:${randomHexPair()}:${randomHexPair()}:${randomHexPair()}:${randomHexPair()}`.toLowerCase());
 }
 
 
diff --git a/server/utils/crypto_utils.py b/server/utils/crypto_utils.py
index ba38b334..23ff03e3 100644
--- a/server/utils/crypto_utils.py
+++ b/server/utils/crypto_utils.py
@@ -72,11 +72,25 @@ def generate_deterministic_guid(plugin, primary_id, secondary_id):
     return str(uuid.UUID(hashlib.md5(data).hexdigest()))
 
 
-def string_to_mac_hash(input_string):
-    # Calculate a hash using SHA-256
+# -------------------------------------------------------------------------------
+def string_to_fake_mac(input_string):
+    """
+    Generate a deterministic fake MAC address from an input string.
+
+    The MAC address is hex-valid and begins with a FA:CE prefix
+    to clearly indicate it is synthetic.
+
+    Args:
+        input_string (str): The input string to hash into a MAC address.
+
+    Returns:
+        str: A MAC address string in the format 'fa:ce:xx:xx:xx:xx'.
+    """
+    # Calculate a SHA-256 hash of the input string
     sha256_hash = hashlib.sha256(input_string.encode()).hexdigest()
 
-    # Take the first 12 characters of the hash and format as a MAC address
-    mac_hash = ':'.join(sha256_hash[i:i + 2] for i in range(0, 12, 2))
+    # Take characters 4–11 (next 4 bytes) to form the rest of the MAC address
+    rest = ':'.join(sha256_hash[i:i + 2] for i in range(4, 12, 2))
 
-    return mac_hash
+    # Prepend the FA:CE prefix to clearly mark this as a fake MAC
+    return f"fa:ce:{rest}"