Are you using a cable company supplied modem straight to your computer or are you using a modem then running it through a router then to your computer
when was the last time you updated your firmware for your modem and/or router?
you should be able to reset both the Modem and the router via the factory reset buttons on the back of the devices
first I would recommend updating the firmware on the Modem and(or) Router, unless it says they are up to date after you do a scan for new firmware update
if they are already up to date or after checking it says their are no new firmware updates available ( or something similar )
then I would hit the reset buttons on the back of the Modem and Router, resetting them back to factory settings
Hope This helps ( also, providing Brand and Model of Modem and Router might be helpful here..... how old are your Modem and Router? )
TC