Turn off Your Wireless Router When Not In Use – Why would you want to do this? When your router is powered off, your network cannot be compromised. Consider doing this when you go on vacation or you will not be using you network for extended periods of time. Just turning off your PC may prevent the PC from being attacked, but it will not prevent someone from breaking into your network via your router if it is powered on.
Bonus Tip – Get in the habit of changing your router password every 30 to 60 days. Also change your PSK several times a year. Changing these two settings may just kick that un-detected guest off your network (take that neighbor!). Limit the maximum number of DHCP users allowed on your network to just the known number of PC's in your house. Limiting this setting can be an indication of someone on your network to you if one of your PC's cannot obtain an IP address from your router.
PSK = Pre Shared Key