Change the default admin password, update firmware, and change default SSID (Service Set Identifier)/password. Default credentials (often "admin/admin") are publicly documented and easily found on the internet — leaving them unchanged gives anyone instant access.

First-priority actions when setting up a wireless router:

1. Change the default admin password — the password used to access the router's configuration GUI (Graphical User Interface)
2. Change the default SSID — "Linksys" or "NETGEAR" tells attackers your router brand and likely vulnerabilities
3. Set a strong Wi-Fi password — use WPA2 (Wi-Fi Protected Access 2) or WPA3 (Wi-Fi Protected Access 3) with a complex passphrase
4. Update the firmware — patch known vulnerabilities

Why defaults are dangerous:

• Router manufacturers publish default IPs, usernames, and passwords in their documentation
• Websites like routerpasswords.com catalog defaults for every router model
• If you don't change the admin password, anyone on your Wi-Fi can reconfigure the router
• Default SSIDs reveal the brand → attacker knows which exploits to try

Accessing the configuration:

• Connect via Ethernet or Wi-Fi
• Open a browser to the router's default IP (typically 192.168.0.1 or 192.168.1.1)
• Log in with default credentials (found in documentation or printed on the router)

Go deeper:

• Default password (Wikipedia) — why unchanged defaults are a major compromise vector (Mirai botnet).
• Residential gateway (Wikipedia) — the all-in-one home router/switch/AP and its default-credential/backdoor risks.