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Article ID: 314455 - Last Review: August 8, 2007 - Revision: 1.4

This article was previously published under Q314455
For a Microsoft Windows 2000 version of this article, see 161986  (http://support.microsoft.com/kb/161986/EN-US/ ) .

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SYMPTOMS

When you attempt to connect to your Internet service provider (ISP), you may receive one of the following error messages:
Error 691: The computer you are dialing in to cannot establish a Dial-Up Networking connection. Check your password, and then try again.
-or-
Error 691: Access was denied because the user name and/or password was invalid on the domain.
-or-
Error 734: The PPP link control protocol was terminated.
-or-
Error 629: The port was disconnected by the remote machine.
-or-
Error 640: A NetBIOS error has occurred.

CAUSE

This behavior can occur if any of the following conditions are true:
  • The settings for your dial-up connection to your ISP are configured incorrectly.
  • The dial-up connection's security option is incorrectly configured to use the Require secured password setting.
  • Your ISP's Point-to-Point Protocol (PPP) server is not functioning properly.
  • You type an incorrect user name or password.

RESOLUTION

To resolve this issue (or issues), use the following methods, as necessary, in the order presented. After you finish each method, check to see whether you can connect to your ISP successfully.

NOTE: You must be logged on as an administrator or a member of the Administrators group to complete these procedures. If your computer is connected to a network, network policy settings may also prevent you from completing these procedures.

Verify Your User Name and Password

  1. Make sure that the CAPS LOCK key has not been accidentally pressed and engaged.
  2. Click Start, point to Connect To, and then click your dial-up connection.
  3. In the Connect dialog box, verify that your user name and password are correctly typed in the User name and Password boxes as provided by your ISP, and then click Dial.NOTE: If you are not sure what your user name and password are, contact your ISP for assistance.

Verify the Phone Number

Verify that you are using the correct phone number to connect to your ISP.

Allow Unsecured Password

Configure your dial-up connection to your ISP to allow an unsecured password. To do this, follow these steps:
  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
  2. Click your dial-up connection, and then click Change settings of this connection under Network Tasks.
  3. Click the Security tab, and then verify that Typical (recommended settings) is selected.
  4. In the Validate my identity as follows box, verify that Allow unsecured password is selected.
  5. Click the Options tab.
  6. Click to clear the Include Windows logon domain check box (if it is selected), and then click OK twice.

Lower the Connection Speed

If phone-line noise or other interference is an issue, you may be able to connect to your ISP by lowering your connection speed. To lower your connection speed, follow these steps:
  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
  2. Click your dial-up connection, and then click Change settings of this connection under Network Tasks.
  3. Click the General tab, click your modem in the Connect Using box, and then click Configure.
  4. In the Maximum speed (bps) box, click 9600, and then click OK twice.
If you are able to connect at a lower speed, or if phone-line noise is such that you cannot connect, request that the phone company check the phone lines.

Disable Hardware Flow Control

Disable the Hardware Flow Control feature in your dial-up connection to your ISP. To do this, follow these steps:
  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
  2. Click your dial-up connection, and then click Change settings of this connection under Network Tasks.
  3. Click the General tab, click your modem in the Connect Using box, and then click Configure.
  4. Click to clear the Enable Hardware Flow Control check box, and then click OK twice.

Disable Modem Error Control

Disable the Modem Error Control feature in your dial-up connection to your ISP. To do this, follow these steps:
  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
  2. Click your dial-up connection, and then click Change settings of this connection under Network Tasks.
  3. Click the General tab, click your modem in the Connect Using box, and then click Configure.
  4. Click to clear the Enable Modem Error Control check box, and then click OK twice.

Disable Modem Compression

Disable the Modem Compression feature in your dial-up connection to your ISP. To do this, follow these steps:
  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
  2. Click your dial-up connection, and then click Change settings of this connection under Network Tasks.
  3. Click the General tab, click your modem in the Connect Using box, and then click Configure.
  4. Click to clear the Enable Modem Compression check box, and then click OK twice.

Disable Software Compression

Disable the Software Compression feature in your dial-up connection to your ISP. To do this, follow these steps:
  1. Click Start, click Control Panel, click Printers and Other Hardware, and then click Phone and Modem Options.
  2. On the Modems tab, click the modem that you want to configure.
  3. Click Properties.
  4. Click the Advanced tab.
  5. Click Change Default Preferences.
  6. In Data Connection Preferences, click Disabled in the Compression list.

Disable LCP Extensions

You may have trouble connecting to your ISP if your ISP's Point-to-Point Protocol (PPP) server does not support Link Control Protocol (LCP) extensions. LCP extensions include a Callback option, a Time Remaining feature, and Identification packets as defined in RFC 1570. Contact your ISP to determine whether you should disable LCP extensions.

To disable LCP extensions, follow these steps:
  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
  2. Click your dial-up connection, and then click Change settings of this connection under Network Tasks.
  3. On the Networking tab, click Settings, and then click to clear the Enable LCP extensions check box.

Disable IP Header Compression

You may experience issues logging on to your ISP if you are using IP header compression (also known as Van Jacobson, or VJ, header compression). To disable IP header compression, follow these steps:
  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
  2. Click your dial-up connection, and then click Change settings of this connection under Network Tasks.
  3. On the Networking tab, click Internet Protocol (TCP/IP), and then click Properties.
  4. Click Advanced, and then click to clear the Use IP header compression check box.
  5. Click OK.

No Message for User Name and Password

If you do not receive a message for your user name or password when you attempt to connect to your ISP, follow these steps:
  1. Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.
  2. Click your dial-up connection, and then click Change settings of this connection under Network Tasks.
  3. Click the General tab, click your modem in the Connect Using box, and then click Configure.
  4. Click the Options tab, click to select the Prompt for name and password, certificate, etc. check box, and then click OK.

Mutual Authentication

You may experience issues logging on to your ISP if your ISP's PPP server is using mutual authentication. Dial-Up Networking does not support mutual authentication. Contact your ISP to determine whether your ISP's PPP server uses mutual authentication. For additional information about modem or dialing problems, click the article numbers below to view the articles in the Microsoft Knowledge Base:
308022  (http://support.microsoft.com/kb/308022/EN-US/ ) Resources for Troubleshooting Modem Problems in Windows XP

MORE INFORMATION

For additional information about how to create a dial-up connection in Windows XP, click the article numbers below to view the articles in the Microsoft Knowledge Base:
305549  (http://support.microsoft.com/kb/305549/EN-US/ ) HOW TO: Configure a Connection to the Internet in Windows XP Professional
308522  (http://support.microsoft.com/kb/308522/EN-US/ ) Description of the Network Setup Wizard in Windows
284269  (http://support.microsoft.com/kb/284269/EN-US/ ) HOW TO: Save and Restore Dial-up Connections

APPLIES TO
  • Microsoft Windows XP Home Edition
  • Microsoft Windows XP Professional
Keywords: 
kberrmsg kbfaq kbnetwork kbprb KB314455
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