Answer: Use an SSH client to access the router configuration.
Change the default administrative username and password
Step-by-step explanation:
Based on the information given, in order to increase the security of the device, it's vital to use an SSH client to access the router configuration. The SSH client refers to the program that helps in establishing an authenticated and secure SSH connections to the SSH servers. It's vital for operating network services securely over a network that's unsecured.
Also, the default administrative username and password should be changed to a more secure username and password which can't be easily known by a third party.