[Firefox, Ubuntu, Linux] WEB GUI "Connection not secure" Installing Self-Signed certificate

[Amplifier]

In this guide > [Troubleshooting] How to fix opening ASUS Router WEB GUI appears “Your connection is not private” | Official Support | ASUS Global > "Method 1: Install certificate (HTTPS certificate only support Google Chrome and Edge)".
It doesn't include Linux and Firefox.

I came across this guide which did work for me > Firefox: Installing Self-Signed certificate on Ubuntu - DEV Community

This is for those that prefer good practice and forming good habits. In this case, following these suggestions.
[Wireless] How to make my router more secure? | Official Support | ASUS Global

Advanced Setting

1. Enable https to log in ASUS router setting page(Web GUI)

Applying a self-signed certificate, you won't have to be conditioned to ignore all the warnings down the road.

You can ignore the warning because your router is a trusted device.

A bit strange, the same paragraph gives good and bad suggestion.

Local Access
Some might not mind themselves or their neighbors walking around with their pants down, so this is for those that prefer to cover their ends.

 

[bbunge]

In this guide > [Troubleshooting] How to fix opening ASUS Router WEB GUI appears “Your connection is not private” | Official Support | ASUS Global > "Method 1: Install certificate (HTTPS certificate only support Google Chrome and Edge)".
It doesn't include Linux and Firefox.

I came across this guide which did work for me > Firefox: Installing Self-Signed certificate on Ubuntu - DEV Community

This is for those that prefer good practice and forming good habits. In this case, following these suggestions.
[Wireless] How to make my router more secure? | Official Support | ASUS Global

Applying a self-signed certificate, you won't have to be conditioned to ignore all the warnings down the road.

A bit strange, the same paragraph gives good and bad suggestion.

Local Access
Some might not mind themselves or their neighbors walking around with their pants down, so this is for those that prefer to cover their ends.

If you only access the router web gui from your LAN who cares if it is http or https? Really, are you going to spy on yourself?

However, a different story for a router in a business location...

 

[Amplifier]

I'm new to this, so I might lack some basic understanding.

I access the router through Wi-Fi locally. I know, not the best option over cables.
I don't track various CVE. I think fewer holes the better. Swiss cheese model - Wikipedia

Those FAQ didn't have instructions for my case. I thought might as well share it. Whether it be useful or not, I have no clue...