How do I reconfigure my router

Do a web search for your router make and model, if you do not have an owner's manual. There is not a one size fits all method to reconfigure router. It may be that your router is an older model that can't be configured to the latest security settings. If this is the case, you may want to consider replacing the router. Check this link for recommended settings....

Recommended settings for Wi-Fi routers and access points - Apple Support