I have the latest appletv and 2 servers (1 local, one external to my home).
When connecting to my local server, I dont have to enter in my username and password. It works great! When I connect to the external server, it requires me to login. Unfortunately, I do need to switch back and forth, and the family isn't doing well with the password stuff.
I have confirmed with the external server owner and there is no reason on their end that would require me to enter a password each time.