Dial-up Networking (DUN) and Remote Access Service (RAS) are included as part of the Microsoft Windows operating system. When Dial-up Networking and Remote Access Service fails, displaying errors on the screen such as errors 621, 667, 669-673, 659, 745 and/or 692, uninstalling and then reinstalling the DUN and RAS services may resolve the issue.
Select the "Start" button, and then click "Settings," and then select "Control Panel" from the list that displays.
Select the "Add/Remove Programs" icon, and the "Add/Remove Programs" window will appear. Select the "Windows Setup" tab, and then select "Communications," item to highlight it, and then select the "Details" button.
Click the "Dial-Up Networking" check box (which will remove the check from the box), and then click the "OK" button.
Select the "Yes" button if a message appears that asks for confirmation to remove "Dial-Up Networking."
Select the "Yes" button when prompted and the computer will reboot and complete the uninstall.
Insert the Windows 95, 98 or ME installation disk into the CD drive.
Click the "Start" button, and then point to "Settings," and then click "Control Panel." Select the "Add/Remove Programs" icon, and then click the "Windows Setup" tab in the window that appears. Double-click the "Communications," item, and then select the "Dial-Up Networking" check box (to place a check in the box). Click the "OK" button.
Select the "Yes" button if prompted to reboot the computer, otherwise reboot the computer to complete the installation.
Click the "Start" or "Globe" button, and then click "Programs" or "All Programs," and then click the "Accessories" program group. If running Windows XP or 2000, click the command line icon. If running Windows 7 or Vista, right-click on the command line icon and then click "Run as Administrator" in the menu that appears. The command line window will appear.
Type "netsh int ip reset c:\resetlog.txt" at the command prompt, and then press the "Enter" key.
Reboot the computer to reset the TCP/IP stack which includes DUN and RAS.
DUN/RAS cannot be uninstalled from Windows 7, Vista, XP or 2000 computers. However, resetting the TCP/IP stack refreshes the registry and files, essentially accomplishing the same task as an uninstall then reinstall of DUN/RAS.