If you are a NOS broadband subscriber, your credentials for Fon are the ones you set up during the router's registration.
Should you have forgotten your password, you can reset it clicking here.
Connecting abroad (outside Portugal)
To connect outside Portugal, make sure you choose NOS or Fon (from the dropdown menu) before starting a session and include NOS/ before your username (email).
For more information about how to connect, please click here.