diff --git a/nixbld-etc-nixos/configuration.nix b/nixbld-etc-nixos/configuration.nix
index bedf19df..ed085e18 100644
--- a/nixbld-etc-nixos/configuration.nix
+++ b/nixbld-etc-nixos/configuration.nix
@@ -140,7 +140,8 @@ in
         iptables -w -A FORWARD -j block-lan-from-wifi
 
         iptables -w -N block-insecure-devices
-        iptables -w -A block-insecure-devices -m mac --mac-source 00:20:0c:6c:ee:ba -j DROP
+        iptables -w -A block-insecure-devices -m mac --mac-source 00:20:0c:6c:ee:ba -j DROP  # keysight SA
+        iptables -w -A block-insecure-devices -m mac --mac-source 74:5b:c5:20:c1:5f -j DROP  # siglent scope
         iptables -w -A FORWARD -j block-insecure-devices
       '';
       extraStopCommands = ''