diff --git a/nixbld-etc-nixos/configuration.nix b/nixbld-etc-nixos/configuration.nix
index a21052b..c4c20ba 100644
--- a/nixbld-etc-nixos/configuration.nix
+++ b/nixbld-etc-nixos/configuration.nix
@@ -138,6 +138,7 @@ in
         iptables -w -A block-insecure-devices -m mac --mac-source 74:5b:c5:21:f1:ee -j DROP  # siglent scope #2
         iptables -w -A block-insecure-devices -m mac --mac-source 00:19:af:5b:dd:58 -j DROP  # power supply
         iptables -w -A block-insecure-devices -m mac --mac-source 28:58:be:dc:66:1f -j DROP  # hikvision low-cost 780nm laser viewer
+        iptables -w -A block-insecure-devices -m mac --mac-source bc:99:11:a4:d2:ac -j DROP  # zyxel cloud switch
         iptables -w -A FORWARD -j block-insecure-devices
       '';
       extraStopCommands = ''