What to do:
Connect to your home router, and change the login name and password. Make sure your WiFi password is strong. Then run through the settings and check that it isn’t unnecessarily letting external connections to devices in your home.
Why do it?
Most WIFI routers come pre-configured from the factory with a default admin user name and password. If you can, change BOTH the user name and password.
Unless you have a real need to access your home devices remotely or are running a home web server, turn off as many (or all) port forwarding & DMZ assignments as possible. Also turn off “ICMP echo requests”, remote management and turn on the built-in firewall of the router.
Doing so minimises the risk of an attacker gaining access to your home router either through WiFi, or remotely through the internet.