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Article ID: 161986 - Last Review: February 20, 2007 - Revision: 2.1

This article was previously published under Q161986
For a Microsoft Windows XP version of this article, see 314455  (http://support.microsoft.com/kb/314455/EN-US/ ) .

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SUMMARY

This article describes how to troubleshoot Internet service provider (ISP) logon problems. This article discusses only logon problems, not modem or dialing problems. For information about modem or dialing problems, see the following articles in the Microsoft Knowledge Base:
ARTICLE-ID: 161516  (http://support.microsoft.com/kb/161516/EN-US/ )
TITLE : Troubleshooting Modem Problems Under Windows NT 4.0

ARTICLE-ID: 162293  (http://support.microsoft.com/kb/162293/EN-US/ )
TITLE : Troubleshooting RAS Client Issues in Windows NT 4.0

MORE INFORMATION

When you attempt to connect to your ISP, you may receive one of the following error messages:
Error 629: The port was disconnected by the remote machine.
Error 640: A NetBIOS error has occurred.
You may experience problems connecting to your ISP for any of the following reasons:
  • The settings for your dial-up connection to your ISP are configured incorrectly.
  • Your ISP's Point-to-Point protocol (PPP) server is not functioning properly.
To determine and resolve the problem you are experiencing, follow the procedures in each of the following sections in order. After you finish each procedure, check to see if you can connect to your ISP successfully.

Verify Your Username and Password

Make sure that Caps Lock is not accidentally on, and then verify that you are typing your username and password exactly as provided by your ISP. If you are not sure what your username and password are, contact your ISP for assistance.

Accept Any Authentication Including Clear Text

Configure your dial-up connection to your ISP to accept any authentication, including clear text. To do so, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Security tab, click Accept any authentication including clear text, and then click OK.

Lower the Connection Speed

If phone line noise or other interference is a problem, lowering your connection speed may allow you to connect to your ISP. To lower your connection speed, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click your modem in the Dial Using box, and then click Configure.
  5. In the Initial Speed (BPS) box, click 9600, and then click OK.
  6. Click OK.
If you are able to connect at a lower speed, or if phone line noise is such that you cannot connect, have the phone company check the phone lines.

Disable Hardware Flow Control

Disable Hardware Flow Control in your dial-up connection to your ISP. To do so, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Basic tab, click Configure, click the Enable Hardware Flow Control check box to clear it, and then click OK.
  5. Click OK.

Disable Modem Error Control

Disable Modem Error Control in your dial-up connection to your ISP. To do so, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Basic tab, click Configure, click the Enable Modem Error Control check box to clear it, and then click OK.
  5. Click OK.

Disable Modem Compression

Disable Modem Compression in your dial-up connection to your ISP. To do so, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Basic tab, click Configure, click the Enable Modem Compression check box to clear it, and then click OK.
  5. Click OK.

Disable Software Compression

Disable Software Compression in your dial-up connection to your ISP. To do so, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Server tab, click the Enable Software Compression check box to clear it, and then click OK.

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, Time Remaining, and Identification packets as defined in RFC 1570. Contact your ISP to determine whether you should disable LCP extensions.

To disable LCP extension, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Server tab, click the Enable PPP LCP Extensions check box to clear it, and then click OK.

Disable IP Header Compression

You may have problems 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, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Server tab, and then click TCP/IP Settings.
  5. Click the Use IP Header Compression check box to clear it, and then click OK.
  6. Click OK.

Connect Using a Terminal Window

Some PPP and SLIP accounts require you to log on using a terminal window, and then type "PPP" or "slip" (without quotation marks) at a terminal prompt to start the session. When you log on, you may also need to prefix your user name with characters such as "P" or "S" or "PPP:" (without quotation marks). Contact your ISP to determine if you must type "ppp" or "slip" at a terminal prompt or if your user name requires a special prefix.

If your ISP requires additional information other than your user name and password, you may need to use a terminal window. To open a terminal window after you connect, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Script tab, click Pop Up A Terminal Window, and then click OK.

No Prompt for Username and Password

If you do not receive a prompt for your user name or password when you attempt to connect to your ISP, follow these steps:
  1. Click Start, point to Programs, point to Accessories, and then click Dial-Up Networking.
  2. Click the phone book entry for your ISP in the Phonebook Entry To Dial box.
  3. Click More, and then click Edit Entry And Modem Properties.
  4. Click the Security tab, click Unsave Password, and then click OK.

Disable Your Login Script

If you run a login script to connect to your ISP, disable it and try to connect with a pop-up terminal window. If you are able to connect, there may be a problem with your login script file. You may need to contact your ISP for assistance in creating a script file to use with Dial-Up Networking. Windows NT includes several basic script files including:
  • Ppp.scp
  • Slip.scp
  • Cis.scp
NOTE: When you use the CompuServe Information Service (CIS) script, you must use your CIS ID for your user name. For more information about using these files, view the Script.doc file in the Winnt\System32\Ras\Script folder. If you have problems creating a script file to automate your log on, contact your ISP for further assistance.

If you have a SLIP account, you must use a terminal window or a script file to connect to your ISP. When you are using a SLIP account, most ISPs display your IP address for the session in the terminal window. Most ISPs inform you of your IP address with a message similar to "Your IP address is <###.###.###.###>" or "SLIP session from <###.###.###.###> to <###.###.###.###>." In this case, the second number is usually your IP address. You should enter this in the IP Address box. If the address is the same every time you connect, you can change it in the phone book entry in TCP/IP settings on the Server tab.

Verify the Phone Number

Verify that you are using the correct phone number to connect to your ISP. If you use MSN, The Microsoft Network, as your ISP, verify that you are dialing in to an MSN phone number that supports calls for the service type "Internet and the Microsoft Network."

Mutual Authentication

You may have problems logging in 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.

PPP Logging

Enabling the PPP logging file (Ppp.log) may help you troubleshoot other problems related to connecting to your ISP's PPP server. For information about how to enable the Ppp.log file, see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: 115929  (http://support.microsoft.com/kb/115929/EN-US/ )
TITLE : Enabling PPP Logging in Windows NT
NOTE: If you are using routing and the Remote Access Service Update, the above Microsoft Knowledge Base article does not apply. For information about enabling logging in this situation, see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: 161426  (http://support.microsoft.com/kb/161426/EN-US/ )
TITLE : How to Enable Logging with Routing and Remote Access

APPLIES TO
  • Microsoft Windows 2000 Server
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional Edition
  • Microsoft Windows 2000 Datacenter Server
  • Microsoft Windows NT Server 4.0 Standard Edition
  • Microsoft Windows NT Workstation 4.0 Developer Edition
Keywords: 
kbfaq kbnetwork KB161986
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