I am using macOS 10.13.1 and Safari 11.0.1, since I upgraded from 10.12 its not possible to access https websites through IP address.
For example:
I want access the config GUI from a router, I open safari go to https://192.168.0.1, safari says: “connection is not private” -> I click “details” -> “open website” -> “visit website” than I have to enter the password from my local user, afterwards the site reloads and again I can see the message: “connection is not private“.

Its a stupid endless loop…
but
If I create a hostname entry in /etc/hosts like: 192.168.0.1 my.funny.router and go to safari and open https://my.funny.router the connection can be established after I clicked “details” -> “open website”

Is there a workaround? Can I disable that “feature”?