Is it a mixed case password for the router?
When entering the router password on the hudl you can change the keyboard so it is typing lowercase or uppercase, make sure you have that right.
On some tablets you can select a "show password" option to see if you are entering it correctly.
Also as has been said, make sure you are trying to logon to YOUR router.
Check the router broadcast name (which should also be printed on the router) to make sure you are logging on to the right one.
Also, a router password can be changed, has anyone ever done that?