Gateway doesn't recognize password when using Admin Tool

I am having problems using the Admin Tool to login to my Gateway.  I enter the user name (admin) and the password that I have been using for years.  I receive a message telling me that the password is incorrect.  The password that I am trying to use is the same password that I use to connect my two iPhones and my Samsung tablet to the Gateway with no connection problems at all.  Visitors to my home have used the password to connect their phones without difficulty.  Is it possible that there is another password that is used to login using the Admin Tool and I have forgotten it?