If you know your router ip address you should be able to access it. see screenshot The modem maybe a different story depending if you own it or if it's from your provider. Google it

Thank you and I agree with you. However, I am using the IP address and it is a non-routable local IP address. This is a browser error and needs to be fixed. A user should never be prevented from going to a website. The user should be notified and made aware but never blocked. And exceptions should be able to be added. This is actually how Firefox used to work but it does not now. Firefox needs to go back to the way it was. This is not productive.

I once had a unit that; If I wanted to access its settings, I had to go thru the provider's website.

Also, this is Firefox on an Android phone, not a PC.

This forum is for Desktop...