|Even if using only one computer, If they did not supply one, I would recommend adding a router between the computer and the cable modem for security reasons. It does not have to be a wireless router unless you want it to be for also using tablets, laptops, and cell phones on your network, but a router will make your computer much more secure. If you do end up using a wireless one, make sure that you change the default password to your own one to remain secure that way as well.|
Yes, your ISP would be the first place you should turn to verify all settings are correct and troubleshoot your connection.
You have to be a little bit crazy to keep you from going insane.