R8000 - Disabling Remote Management

Hey guys, trying to get some help. I have a R8000 router. I am trying to disable any kind of remote management, or management done to the router by any devices connected to the network wirelessly.

First Attempt:

So I tried going into the router admin page, 192.168.1.1. I go under advanced > select security > advanced management. But all it shows me is to "Always use HTTPS to access router"

2nd Attempt:

I opened the Guest Access point. I enabled Broadcast of SSID, and Enabled the Guest network, but I leave the box "Allow guests to see each other and access my local network" Unchecked. Now I tried to test it, by logging in through one of my devices, as soon as I type 192.168.1.1, it just prompts me like normal, and I can still access the router just like normal.

Even though under Netgear help it still says "When unchecked, users connecting to this guest network can only access the Internet and cannot access any other devices in the same network or in other networks, including the main network and the wired network. In addition, all the clients in this guest network cannot access router's management GUI or any other services provided by the router (for example, ReadySHARE Storage, ReadySHARE Printer... if the router supports these functions)."

So is this a glitch in Netgears security? I mean if the company really wanted to be most secure, wouldnt they give you the option to allow only ethernet management, rather than online based management?

Does anyone have a sure workaround, where I can disable any modification to the router by a device connected wirelessly? Thanks