The information in this article applies to:
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:
When you attempt to connect to your ISP, you may receive one of the following error messages:
You may experience problems connecting to your ISP for any of the following reasons:
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:
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:
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:
Disable Modem Error Control
Disable Modem Error Control in your dial-up connection to your ISP. To do so, follow these steps:
Disable Modem Compression
Disable Modem Compression in your dial-up connection to your ISP. To do so, follow these steps:
Disable Software Compression
Disable Software Compression in your dial-up connection to your ISP. To do so, follow these steps:
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.
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:
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.
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:
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:
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.
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."
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.
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:
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:
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