What should be changed immediately for security when setting up a wireless router?

Changing the administrator password is crucial for security when setting up a wireless router. The administrator password provides access to the router's management interface, where settings can be adjusted and security protocols can be configured.

Many routers come with a default administrator password that is widely known or can be easily found online. If this default password is not changed, anyone who knows or can find this information can gain unauthorized access to the router. This could allow an attacker to change configurations, view sensitive data, or even take control of the entire network.

Thus, securing the administrator password is the first line of defense in protecting the network from potential threats and unauthorized access. It's essential to create a strong, unique password that would be difficult for an intruder to guess. This proactive step is fundamental before moving on to other configurations related to security, such as changing the network name or SSID and selecting a wireless channel.