"webGUI" seems fine to me, as your question concerns the web based GUI.
If your looking for the perfect "security", make it a none issue.
Like : Make the WebGUI only accessible on the LAN interface.
Activate LAN type another interface (initially called OPT), and use a firewall rule to forbid any "local" web GUI access.
Remove all devices from the LAN port.
This way, the question is resolved, as the question became irrelevant.
The only web to admin the device is to connect physically a cable into the LAN port : the admin has to have physical access to (into) the device.
..... humm : a SG1000 only has two ports, which is rather minimalistic
Next best : Set up a OpenVPN if you need to connect to the webgui remotely.