There are a number of reasons why a computer might kick its user off the Internet, including issues with the modem's programming or connection to the main Internet server. Other possible reasons are a faulty modem or modem cable or a computer virus interfering with the connection. Several diagnostic tools are available to help determine the nature of the problem and solve it, according to Computer Hope.
One of the most common reasons for a modem to disconnect frequently is an internal programming issue, says Computer Hope. This can be fixed by manually resetting the modem by switching the device off for a few minutes and then switching it back on. One can do this by unplugging the modem, or by using the power button located on the back or side.
Windows operating systems come with a modem troubleshooting wizard installed. To access the wizard, right click on the Internet connection icon in the lower right corner of the screen. Select the "troubleshoot problems" option from the list. This troubleshooter detects and automatically solves some of the most common problems by refreshing the Internet connection and checking to see that the proper ports are open. It also provides an analysis of issues it cannot automatically correct.