Microsoft, in their continuing effort to keep writers from writing, has again changed the location of this control in Windows 10 to make it even harder to find. Here's the updated method:

Settings...

I'm not sure that's true. I get the same dialog, and the same exception, if I disconnect the WAN uplink and try connecting to the router. That means myfiosgateway.com is a hardcoded pointer to...

My guess is that they do have a real certificate for released firmware, but that they use a self-signed one internally for development, and somebody dropped the ball and left the reference to that...

I tried it, per your instructions. Portable Firefox 38 also detects it as an untrusted site.

The certificate is not expired. In fact, it was issued October 2, 2015 and expires September 29, 2025. The problem is that it is self signed, issued to (and by) GreenWave Systems.

Apparently...

The same thing just happened to me. 192.168.1.1 sends me to a web page that redirects me to myfiosgateway.com. When I go there I get the security warning. Not sure why a connection to a local IP...