I suspect someone use my internet without any authorozation. He is a tenent in my house ,how can I prevent that? I try to change my password but he use the serial number from my modem . we share the apartment and there is not modem plug in point inside my private room , what can I need to do ?
Just having the serial number will not give him access..
He would have to have the password you set on the modem. OR he would have to have physical access to the modem to plug a computer wired into it.
Beyond setting a password for the wireless... which should prevent them from getting on that way (unless they figure it out). The only othe way is to prevent them from physically accessing the modem. (as with that, they could always do a full reset to reset the wireless password on you, etc)