These days I am playing with IPv6 and tried to access few sites directly by IP address.
It looks like the browsers are trying to interpret the IPv6 address as name:port and the connection of course fail.
If you type directly in the browser, for example:
you will get error message.
If you want this to be interpreted as IPv6 address you will have to type the address like this:
I tested this on Linux with the following browsers: