When you connect to your InvizBox 2 and access the Administration Interface using your browser you get a message stating that the InvizBox 2's Administration Interface is not secure.
When you are accessing http://inviz.box you are not accessing a website on the internet. You are actually accessing content that is stored on your InvizBox 2, this is the interface that allows you to change settings on your InvizBox 2 which is in your house.
Why HTTP and not HTTPS
Most websites would encrypt the data they send to you (and you send to them) using HTTPS. HTTPS requires a certificate which needs to be renewed over time. Since the InvizBox 2's Administration Interface is hosted on the InvizBox 2 itself this poses some technical limitations when it comes to renewing these HTTPS certificates. This is why we use HTTP as it does not require a certificate.
However as you are accessing local content that is on the InvizBox 2 there is no need to encrypt it, but since your browser doesn't know that you are only accessing local content it flags the page as "Not Secure". In fact the Administration Interface is perfectly secure because the only people who can access it are those connected to the InvizBox 2 directly.
HTTPS is still an option
You can access the Administration Interface using https://inviz.box if you wish. Your browser will throw an error that the website is not safe due to the self signed certificate that the Administration Interface is using. Depending on your browser (we use Firefox here) you should be able to accept the certificate and access Administration Interface.