See if you can find it inside your router/modem (acessabe by your browser)....if you have set the time and date on it, it probably contains a log file, but it has to be turned on ....
I have a cable modem that is also my wireless router. I have a desktop connected to my router and two laptops at home. Is there any way to log the usage of the wireless connection from the desktop? I want to know when the wireless was used, what hours of the day (what they were using it for is less important but might be nice). I know there are programs that I can track if I install them on the laptop, but for this case that is not possible.