routerlogin.net

hi all, so this is a 2 part question:

1.   cannot log in to the "routerlogin.net" on my new macbook air but can still login on the macbook pro.  any idea why?  on the pro as soon as i type that into the search bar it logs me right in without asking for a password.  but when i try to login on the air it asks for username and password.  

2.  so whatever username and password i put in nothing works.  i try username and password that is on the bottom of the router and it doesn't work.  finally it asks for serial number and security questions to which i can't remember one of the answers. 

if anyone can help with 1 or both questions Id really appreciate it.  Thanks so much.