Troubleshooting network and dial-up connections

What problem are you having?

The modem does not work.

Cause:  The modem is incompatible.

Solution:  If you have access to another computer with an Internet connection, check the list of compatible modems. For a comprehensive list of hardware supported by Windows operating systems, see Compatible Hardware and Software in Help and Support Center.

Cause:  The modem is not connected properly or is turned off.

Solution:  Verify that the modem is connected properly to the correct port on your computer. If the modem is external, verify that the power is on.

See Also:  Troubleshooting Modems

Unable to connect to my Internet service provider (ISP).

Cause:  The ISP's server is not running.

Solution:  Ask your ISP to verify that the remote access server is running.

Cause:  You do not have a valid user account, or you do not have remote access permission.

Solution:  Verify with your ISP that your user account has been established, and that you have remote access permission.

Cause:  You dialed the wrong number, or you dialed the correct number but forgot to dial an external line-access number, such as 9.

Solution:  Verify that the number is correct as dialed.

Cause:  Your modem cannot negotiate with the modem of the server.

Solution:  Try using the same type of modem as the server.

Cause:  The modem cabling is faulty.

Solution:  Do not use the 9-to-25-pin converters that are included with most mouse hardware because some of them do not carry modem signals. To be safe, you should use a converter made especially for this purpose.

Cause:  The telephone line (for example, in your hotel room) does not accommodate your modem speed.

Solution:  Select a lower bits-per-second (bps) rate (or call the hotel manager to request a direct line).

See also:  To change the maximum modem port speed

Cause:  The line you are trying to use is digital.

Solution:  Most modems work only with analog phone lines. Verify that you have analog phone lines installed or, if you have digital phone lines installed, verify that the servers and clients have digital modems.

When trying to connect, a message is received that says the ISP server is not responding.

Cause:  

At higher bits-per-second (bps) rates, your modem is incompatible with the modem of the server.

There is a lot of static on the phone line, which prevents a modem from connecting at a higher bps rate.

There is some kind of switching equipment between the client and server that prevents the two modems from negotiating at a higher bps rate.

Solution:  Adjust the speed of your modem to a lower bits-per-second (bps) rate.

See also:  To change the maximum modem port speed

Cause:  The ISP server is not running.

Solution:  Ask your ISP to verify that the server is running.

The modem always connect at a lower bits-per-second (bps) rate than specified.

Cause:  The modem and telephone line are not operating correctly. Excessive static on the telephone line causes sessions to be dropped.

Solution:  You can use modem diagnostics to confirm correct modem operation.

See also:  To log and view modem commands

Cause:  The quality of your line is insufficient.

Solution:  Contact your telephone company to verify the quality of your line.

Cause:  The line you are dialing is affecting the speed.

Solution:  If you can connect to your ISP by using more than one number, try another number and see if the speed improves.

Cause:  Your modem software needs to be updated.

Solution:  Check with your modem manufacturer for modem software updates.

The sessions with my ISP on the network keep getting dropped.

Cause:  Call waiting is disrupting your connection.

Solution:  Verify that the phone has call waiting. If so, disable call waiting and try calling again.

See also:  To change dialing properties for a location

Cause:  The ISP disconnected you because of inactivity.

Solution:  Try calling again.

Cause:  Someone picked up the phone. Picking up the phone automatically disconnects you.

Solution:  Try calling again.

Cause:  Your modem cable is disconnected.

Solution:  Verify that the modem cable is connected properly.

Cause:  Your modem software needs to be updated.

Solution:  Check with your modem manufacturer for modem software updates.

Cause:  Your modem settings need to be changed because the ISP changed settings on their server.

Solution:  Verify the modem settings with your ISP's system administrator.

Connections are disconnecting abnormally.

Cause:  The ISP server is not running.

Solution:  Ask your ISP system administrator to verify that the server is running.

Cause:  

Your modem is unable to negotiate correctly with the modem of the ISP server.

The serial port of the computer cannot keep up with the speed you have selected.

Solution:  Try to connect at a lower initial port speed.

See also:  To change the maximum modem port speed 

Cause:  Your modem software needs to be updated.

Solution:  Check with your modem manufacturer for modem software updates.

When trying to connect, a hardware error is received.

Cause:  The modem is turned off.

Solution:  Verify that the modem is turned on. If the modem is turned off, turn it on and redial.

Cause:  Your modem is not functioning properly.

Solution:  Enable modem logging to test the connection.

See also:  To log and view modem commands

Cause:  Your cable is incompatible.

Solution:  If your modem communicates through Terminal, but not through Network Connections, the cable that attaches your modem to the computer is probably incompatible. You need to install a compatible cable.

Conflicts between serial ports are causing connection problems.

Cause:  The serial ports are conflicting.

Solution:  Com1 and Com3 share interrupt request (IRQ) 4. Com2 and Com4 share IRQ 3. As a result, for serial communications, you cannot use COM1 and COM3 simultaneously, or COM2 and COM4 simultaneously. For example, you cannot use Network Connections on COM1 and Terminal on COM3.

This rule applies if you are using the mouse in addition to other serial communications programs such as Network Connections or the Terminal program. The rule does not apply if you are using an intelligent serial adapter such as a DigiBoard serial card.

See Also:  To configure a connection; To change the COM port for a modem

When trying to connect by using ISDN, a "No Answer" message is received.

Cause:  The ISP server did not answer because it is turned off or the modem is not connected.

Solution:  Contact your system administrator.

Cause:  The line is busy.

Solution:  Try calling later, or contact your system administrator.

Cause:  There is a problem with the hardware.

Solution:  Verify that the ISDN adapters are installed and configured correctly.

Cause:  Your phone number is not configured correctly.

Solution:  In some cases, each B channel on an ISDN line has its own number, while in other cases both B channels share a single number. Your telephone company can tell you how many numbers your ISDN line has.

Cause:  If you are located in the United States or Canada, your Service Profile Identifier (SPID) is configured incorrectly. The SPID normally consists of the phone number with additional digits added to the beginning, the end, or both. The SPID helps the switch understand what type of equipment is attached to the line and routes calls to appropriate devices on the line. If an ISDN channel requires a SPID, but it is not entered correctly, then the device cannot place or accept calls.

Solution:  Verify that the SPID is entered correctly.

Cause:  A poor line condition (for example, too much static) interrupted your connection.

Solution:  Wait a few minutes and try dialing again.

Cause:  You did not enable line-type negotiation, or a connection cannot be made with the line type you selected.

Solution:  Enable line-type negotiation.

Cause:  Your ISDN switching facility is busy.

Solution:  Try again later.

Cause:  Your DigiBoard card is too old.

Solution:  If you do not have the latest PCIMAC-ISA DigiBoard card, serial number A14308 or greater, contact DigiBoard for a replacement.

Connections made by using X.25 fail.

Cause:  The dial-up PAD is configured with the wrong X.3 parameters or serial settings.

Solution:  If the remote access server is running and you cannot connect to it directly through an X.25 smart card or an external PAD, modify the dial-up PAD X.3 parameters or serial settings. Ask your system administrator for the correct settings.

See also:  To configure a connection

Cause:  New Pad.inf entries are incorrect.

Solution:  You can check other Pad.inf entries for direct connections and external PADs, and view the comments that go with them. You may need a line analyzer or a terminal program to see the response for the PAD. For dial-up PAD entries, you can use an entry in Pad.inf as an example, paying attention to the comments that go with the example.

Cause:  Your modem is incompatible.

Solution:  If the modem that connects to a dial-up PAD connects at a lower speed than it should, replace the modem with a compatible one.

See also:  The modem does not work with Network Connections

Cause:  The line for the remote access server is congested. If a connection has been established, but the network drives are disconnecting, and you are dropping sessions or getting network errors, the cause may be congestion on the leased line for the remote access server.

For example, four clients connecting at 9600 bps (through dial-up PADs) require a 38,400-bps (four times 9600) leased line on the server end. If the leased line does not have adequate bandwidth, it can cause time-outs and degrade performance for connected clients. This example assumes that Routing and Remote Access is using all the bandwidth. If Routing and Remote Access is sharing the bandwidth, fewer connections can be made.

Solution:  Your system administrator needs to verify that the speed of the leased line can support all the COM ports at all speeds clients use to dial in.

Connections through PPTP fail.

Cause:  TCP/IP connectivity problems are keeping you from connecting to the PPTP server.

Solution:  You or your system administrator can use the ipconfig and ping commands to verify a connection to your server.

Cause:  A Winsock Proxy client is active.

Solution:  A VPN connection cannot operate with an active Winsock Proxy client. Winsock Proxy immediately redirects packets to the proxy server before they can be processed by a virtual network connection for encapsulation. Ask your system administrator to disable the Winsock Proxy client.

Cause:  You do not have the appropriate connection and domain permissions on the remote access server.

Solution:  Contact your system administrator.

Cause:  If you are using the TCP/IP protocol, you do not have a unique TCP/IP address.

Solution:  Contact your system administrator.

Cause:  Name resolution problems are keeping you from resolving names to IP addresses.

Solution:  Specify fully qualified domain names and IP addresses in your connection.

See Also:  To configure TCP/IP settings

Connections made by using PPP or TCP/IP utilities are failing.

Cause:  The server does not support LCP extensions.

Solution:  If you cannot connect to a server by using PPP, or the remote computer terminates your connection, the server may not support LCP extensions. In Network Connections, clear the Enable LCP extensions check box.

Cause:  IP header compression is keeping TCP/IP utilities from running. If you successfully connect to a remote server by using PPP, but TCP/IP utilities do not work, the problem may be IP header compression.

Solution:  Try to reconnect after turning off IP header compression.

See Also:  To stop requesting LCP extensions in PPP; To turn off IP header compression in PPP

A specific program experiences Internet connectivity issues and Internet Connection Sharing, Internet Connection Firewall, or both are enabled.

Cause:  Internet Connection Firewall, Internet Connection Sharing, or both are obstructing the program or prohibiting the program from successfully establishing full, two-way communications across the Internet.

Solution:   Obtain an Internet Connection Sharing and Firewall plug-in from the program manufacturer. Internet Connection Sharing and Firewall plug-ins are designed to fix any Internet connectivity problems that you may encounter with specific programs when either Internet Connection Sharing (ICS) or Internet Connection Firewall (ICF) are enabled. The plug-ins are provided on disk or over the Internet as an executable file. Because Internet Connection Sharing and Firewall plug-ins can potentially open your network to security risks, you should only install them when they are from a trusted source. For more information, see Using Internet Connection Sharing and Firewall Plug-ins

Connections made by using Internet Connection Sharing are failing.

Cause:  The wrong LAN network adapter is shared.

Solution:  A computer with Internet Connection Sharing needs two connections. One connection, typically a network adapter, connects to the computers on the home or small office network and the other connection connects the home or small office network to the Internet. You need to ensure that Internet Connection Sharing is enabled on the connection that connects your home network to the Internet.

Cause:  TCP/IP is not installed on home or small office network computers.

Solution:  By default, the TCP/IP protocol is installed on computers running Windows XP, Windows 2000, Windows Millennium Edition, Windows 98, and Windows NT version 4.0. If users on your home or small office network are running operating systems other than these, verify that TCP/IP is installed on their computers.

Cause: If users on your home or small office network cannot reach the Internet, TCP/IP is incorrectly configured on their computers.

Solution: Verify that the following TCP/IP settings are established on local area connections:

IP Address: Obtain an IP address automatically (through DHCP)

DNS server: Obtain DNS server address automatically

Default gateways: None specified

For computers running Windows 95, Windows 98, Windows Millennium, or Windows NT version 4.0, you can find the TCP/IP settings in Network in Control Panel.

Cause: If users on your home or small office network cannot reach the Internet, their Internet options need to be modified.

Solution: Internet options must be modified for Internet Connection Sharing. For more information, see To configure Internet options for Internet Connection Sharing

Cause:  The Internet Connection Sharing service is not started.

Solution:  Use Event Viewer to verify that the Internet Connection Sharing service is started.

See also:  Using Event Viewer

Cause:  The Internet Connection Sharing computer is not properly configured for name resolution.

Solution: You may need to configure the WINS or DNS name resolution services on the computer. If computers on the home or small office network cannot resolve names to IP addresses, you can check the name resolution configuration of the Internet Connection Sharing computer by using the ipconfig command. There are two ways that your ISP can configure name resolution:

Statically assigned name servers

You must manually configure the TCP/IP protocol with the IP address (or addresses) of the name servers provided by the ISP. If you have statically assigned name servers, you can use the ipconfig command at any time to get the IP addresses of your configured name servers.

Dynamically assigned name servers

Manual configuration is not required. The IP addresses of the name servers provided by the ISP are dynamically assigned whenever you dial the ISP. If you have dynamically assigned name servers, you must run the ipconfig command after a connection to the ISP has been made.

Cause:  If you cannot play a game across the Internet, the protocol used by the application is not translatable.

Solution:  Try running the program from the Internet Connection Sharing computer. If the program works there but not at another computer on the home or small office network, then the program may not be translatable.

Cause:  If you cannot play a game across the Internet, the program is not configured on the computer running Internet Connection Sharing.

Solution:  Verify that the program, including port numbers, is configured correctly.

See also:  Programs and services overview

Cause:  If Internet users cannot see services on your home or small office network, such as a Web server, the service is not configured correctly.

Solution:  Verify that the service, including port numbers and TCP/IP addresses, is configured correctly.

Cause: If users on your home network cannot reach the Internet sites by using friendly names, there is a DNS resolution problem.

Solution:  Have users on your home network use fully qualified domain names or IP addresses when accessing Internet resources.

See Also:  Service definitions overview; Internet Connection Sharing; To configure TCP/IP to use WINS; To configure TCP/IP to use DNS; To test a TCP/IP configuration by using the ping command

When using a local area network connection, there is no response.

Cause:  There may be problems with your network adapter.

Solution: Try the following:

Check the appearance of the local area connection icon. Depending on the status of the local area connection, the icon appears in different ways in the Network Connections folder. Also, if the local area connection media is disconnected (for example, the cable is unplugged), a status icon is displayed in the notification area. For more information, see Local area connections 

Use Device Manager to verify that your network adapter is working correctly.

Cause:  The local area connection cable may not be plugged into the network adapter.

Solution:  Check to make sure the local area connection cable is inserted into the network adapter.

When using a laptop to connect to an ISP, some or all of the programs do not run properly.

Cause:  The WinSock Proxy Client may be preventing your programs from running properly when you use the ISP connection.

Solution:  If you are a mobile user and use your laptop in your corporate environment, you may need to disable the Microsoft WinSock Proxy Client (WSP Client in Control Panel) when you use the same computer to dial to an ISP or other network. For example, if you use a laptop in your office and use the same computer to connect to an ISP or other network from your home, you may have problems running all of your applications when you use the ISP connection. (For example, your programs may not be able to find the resources or servers they need.) If this is the case, you should disable the Microsoft WinSock Proxy Client (WSP Client in Control Panel) to run the programs that you typically run when you use your laptop in the corporate office.

Incoming connection clients cannot see resources beyond the incoming connection computer.

Cause: If the addresses that are being allocated to incoming clients are not a subset of the network to which the incoming connection computer is attached, you must create a route to the incoming client computers on the intranet computers.

Solution: Reconfigure your range of IP addresses that are being allocated to incoming clients so that it is a subset of the network to which the incoming connections computer is attached. If you cannot do this, then configure your intranet hosts with the IP address of the incoming connections computer as a default gateway.

If your intranet hosts are configured to obtain an IP address automatically and a Dynamic Host Configuration Protocol (DHCP) server is present, you can configure your DHCP server to assign the default gateway.

If your intranet hosts are configured to obtain an IP address automatically and a DHCP server is not present (you are using the Automatic Private IP Addressing feature), then you must manually configure all of your intranet hosts with an IP address, subnet mask, and default gateway.

See Also: To configure a default gateway, Incoming connections and IP addresses

Cause: The calculated range of addresses allocated to connecting clients is larger than the range that you configured.

Solution: Most TCP/IP networks use subnets in order to effectively manage routed IP addresses. The closest matching subnet is calculated for the range that you specified in From and To. The range of addresses in the closest matching subnet may exceed the range that you specified. Unless the addresses specified in From and To are subnet boundaries, the range based on the calculated subnet will be larger than the range that you specified. To avoid this, specify a range that falls on subnet boundaries. For example, if you are using the 10.0.0.0 private network ID for your intranet, a range that falls on subnet boundaries is 10.0.1.168 to 10.0.1.175. Or, if you are using the 192.168.0.0 private network ID for your intranet, a range that falls on subnet boundaries is 192.168.1.0 to 192.168.1.255.

See Also: To configure an incoming connection to use TCP/IP



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