192.168.l.254 is a specific IP address assigned for internal use of some brands of routers that was set by the manufacturer. Essentially, 192.168.l.254 gives the user access to the internal software settings of the router or modem.
Some of the brands that utilize 192.168.1.254 include:
Westell DSL Modems (US ONLY)
Netopia / Cayman Gateways
192.168.1.254 is also a private address in the IP version four or IPv4 address space.
You can setup any device to use it but it can only be used by one device at a time accordingly. 192.168.1.254 is set at the factory, however the manufacturers usually always allow this setting to be changed. If you use your devices internal software, you should have no problem changing it.
The group of IP addresses that 192.168.1.254 belong to being private, do not allow external access or access from other devices which are located outside of the network. If you open your browser to 192.168.1.254, you should be presented with a username and password request. 192.168.1.254 also essentially loads the authentication step for entry into the console software that operates your device. Loading 192.168.l.254 should open the administration console.
All configurable settings are located within this software as well. If you want to make a change to your default gateway or change your address from the default 192.168.1.254, you can make those changes within this console. Default usernames and passwords are usually the common combination.
You should search the web or consult your manual for specific username and password combinations for logging into your device. 192.168.1.254 is essentially a popular manufacturers choice for accessing the administration console of some devices.