Cable Modem Troubleshooting Tips

Intro & Index.
Update history.
Installer issues.
Registration issues.
Network setup.
Mobile setup.
Cable Modem LEDs.
IP addresses.
MAC addresses.
Dead connection.
System updates.
Network tweaks.
Ethernet issues.
USB issues.
Surfboard tips.
CM diagnostics.
CM config file.
CM tech info.
DHCP issues.
DNS issues.
Web proxy issues.
Streaming media.
Gaming issues.
P2P file-sharing.
SETI@home issues.
Faster web browsing.
Faster downloads.
Simul down/uploads.
Swapping PCs on CM.
PCs sharing CM.
Simul dialup & CM.
VPN issues.
Time sync.
Virus security.
Firewall security.
Speed testing.
Latency issues.
Traceroute.
Packet loss.
FrontPage tips.
NTL/BY Tech Support.

Basic Network Settings

The settings you need to configure a machine to use the ntlworld cable modem service are available at: http://www.ntlworld.com/help/settings.htm, subject to the following error as at 2001 March 30 (the following information derived from recent posts in ntl.announce):

The current news NNTP server for the cable modem service is:

newscache.cable.ntlworld.com (this change was posted on newsgroup ntl.announce on 2002 March 21)
news.cable.ntlworld.com (the previously published setting, still working but with a reduced number of allowed simultaneous connections).

The settings for the blueyonder service are available at: http://help.blueyonder.co.uk/server.html.

The DNS server addresses that are issued to you by DHCP lease may differ from the ones listed by your ISP. You should not configure explicit DNS servers, but allow them to be discovered automatically by DHCP, as your ISP can change the DNS server addresses from time to time. The only users who might need to code DNS server addresses explicitly are those who run a private LAN behind a router, with no local DHCP service.

If you know how to apply the above information, you don't need NTL's Broadband Installer CD-ROM. This enables you to get notionally unsupported systems such as Mac OS X and Linux up and running.

NTLworld provide an illustrated guide at http://www.ntlworld.com/help/cm.htm to manually setting up Win9x/ME and Apple Mac OS 8.x/9.x for the cable modem service. There is little in the guide that is NTL-specific and it can be followed by users of other ISPs such as Blueyonder. As at 2001 March 30 there are errors in this guide as follows:

In Internet Options, Local Area Network Settings, the option Automatically detect settings should be UNchecked, not checked. NTLworld does not offer a WPAD service, so leaving this option checked would slow down Internet Explorer launches.
In TCP/IP Properties, WINS Configuration, I am sceptical about checking Use DHCP for WINS Resolution, as I doubt that NTLworld offers WINS services, and I prefer Disable WINS Resolution.
Under use of winipcfg, only the old 62.* series of addresses is listed: there are now addresses in the 213.* and 80.* ranges. Other ISPs will use different IP address ranges.

After manual network configuration, you need to:

[if using a digital TV set top box as a cable modem] register the PC's MAC address with the STB;

execute the post-installation registration procedure, in order to turn your cable connection on properly.

Blueyonder do not provide an online guide to manual configuration for their cable modem service; see http://help.blueyonder.co.uk/setup/hsiconfig.html. However, the NTL illustrated guide at http://www.ntlworld.com/help/cm.htm can be followed fairly safely (see above). See http://help.blueyonder.co.uk/setup/userguide.html for online copies of the latest versions of the User Guides in PDF format. The by-Users site has additional help at http://www.by-users.co.uk/faqs/cablemodems/.

Windows 2000 and XP setup

Instructions for setting up Windows 2000/XP for cable modem service from a typical ISP are given here.

NTL provide an online installation guide, including links to downloads for XP-compatible USB drivers for the Surfboard 4100 and Terayon TeraJet 210. These drivers might be more recent than the ones supplied on the CD-ROM with the cable modem.

No special driver for the cable modem is required if you will be using an ethernet connection: you just need the driver for the ethernet card, many of which are automatically recognised by Windows.

If you will be using a USB connection to the cable modem, you will first need USB drivers compatible with Windows 2000/XP (the ones supplied on CD-ROM with your cable modem might not be up to date):

For the latest USB drivers for the Surfboard 4100, see http://www.gi.com/noflash/usb_drivers.asp.
For the latest USB drivers for the Terayon TeraJet series, go to http://www.terayon.com/, click the Support link, click TeraJet DOCSIS Cable Modems, then click the link for USB drivers.

You will need to un-Zip the downloaded file to obtain the driver files. You would then install these drivers in preference to the ones on the CD-ROM supplied with the cable modem, by manually navigating the Windows driver installation wizard to the new driver files.

The following instructions for configuring the network connection assume that you might be converting to cable from some previous network use, and therefore include elimination of previous configuration data: for a fresh connection, the previous data might not be present.

Open Control Panel.
Double-click [2000] Network and Dial-up Connections, or [XP] Network Connections.
Identify the icon for your cable modem connection: it is usually Local Area Connection. If you have both ethernet and USB cable modem drivers active, you might have two icons, labelled Local Area Connection and Local Area Connection 2. You can distinguish them by right-clicking each, selecting Properties, and viewing which hardware interface each is connected to. Note: with Windows 2000/XP and USB-connected cable modems, these connection icons might disappear from the control panel if the USB connection is unplugged or the cable modem powered off.
Right-click the appropriate icon and select Properties.
[XP only] Ensure the General tab is at the front.
In the central box (scroll if necessary), if the component Internet Protocol (TCP/IP) is absent, then:

Click the button Install...
Select Protocol and click Add...
[2000 only] In the box Manufacturers select Microsoft, and
[2000/XP] in the box Network Protocol select Internet Protocol (TCP/IP).
Click OK.

In the central box (scroll if necessary), uncheck all components except Internet Protocol (TCP/IP) and (optionally) Client for Microsoft Networks. For security, if your PC is connected directly to the cable modem, you should ensure that File and Printer Sharing for Microsoft Networks is unchecked.
In the central box (scroll if necessary), select Internet Protocol (TCP/IP), and click button Properties.

Check Obtain an IP address automatically.
Check Obtain DNS server address automatically.
Click button Advanced...

With tab IP Settings at the front:

If there are any entries in box Default gateways, select each and click Remove. See http://support.microsoft.com/support/kb/articles/Q244/3/99.ASP for more.

Click tab DNS to bring it to the front:

If there are any entries in box DNS server addresses, in order of use, select each and click Remove.
UNcheck Append these DNS suffixes (in order).
In box DNS suffix for this connection you may enter a default DNS domain for your ISP, e.g. ntlworld.com or blueyonder.co.uk or you may leave this box blank.
UNcheck Register this connection's addresses in DNS. See http://support.microsoft.com/support/kb/articles/Q263/5/50.ASP for more.

Click tab WINS to bring it to the front:

If there are any entries in box WINS addresses in order of use, select each and click Remove.

Click OK to exit the Advanced settings.

Click OK to exit Internet Protocol settings.

[Win XP only] Click OK to save the changes you have made and exit the Connection properties, then come back again by right-clicking the connection icon and selecting Properties.
If this is an ethernet connection, and if your cable modem's ethernet interface is not specifically listed as capable of full-duplex working (see list), click the button Configure below the adapter name.

Click the tab Advanced to bring it to the front:

In the Property box, the property name to be selected varies according to model of ethernet card. Examples are: Network Link Selection, Media Type, Connection Type, Duplex Mode, or any similarly-named property which can have Values looking like Auto-Negotiation, or 10BT, or 10BaseT.
In the Value box, select a value which either (a) explicitly says half-duplex or semi-duplex, or (b) at least does not say full-duplex [e.g. 10BaseT on its own is OK]. If there is a choice between 10 and 100 with half-duplex, choose the 10. Do not choose 10Base5, 10Base2, or AUI.

Click OK to exit the Adapter settings.

Click OK to exit the Connection properties.
Close the Network and Dial-up Connections window.
Continue with Internet Options setup below.

Windows all versions: Internet Options setup

Open Control Panel.
Double-click Internet Options.
Click on the tab Connections to bring it to the front.
Check Never dial a connection.
Click on button LAN Settings...

UNcheck Automatically detect settings (unchecking this speeds up IE launches).
UNcheck Use automatic configuration script.
UNcheck Use a proxy server (unless you want an explicit setting).
Click OK to exit Local Area Network settings.

Click OK to exit Internet Options.

Windows XP built-in firewall

Some users report difficulties getting Windows XP to work when first connected. It is possible that the built-in firewall might be causing problems with the strange requirements of the cable modem DHCP system. It is suggested that you should not enable the built-in firewall until after (a) you have a working cable connection, and (b) you understand how to configure the built-in firewall. You should only consider enabling the firewall if your XP PC is directly connected to the cable modem. You should disable the firewall if there is a NAT router and/or home LAN between the XP PC and the cable modem.

Open Control Panel.
Double-click Network Connections.
Right-click the appropriate connection icon, and select Properties.
Click on tab Advanced to bring it to the front.
To enable the firewall, check Protect my computer (etc); or
To disable the firewall, uncheck Protect my computer (etc).
Click on button Settings...

With tab Services at the front:

check any services offered on your PC that you wish outside users to be able to connect to. If there are no such services, uncheck all boxes.

Click tab ICMP to bring it to the front:

check Allow incoming echo request.
check all the Allow outgoing options.

Click OK to exit Advanced Settings.

Click OK to exit Connection Properties.

Mac OS 8.x-9.x setup

See http://www.ntlworld.com/help/cm.htm#macconfig for an illustrated guide which is generic for all cable systems requiring DHCP.

You might also have to configure e-mail, news, and FTP client applications with your ISP's settings.

NTLworld e-mail, news, and FTP client settings are at http://www.ntlworld.com/help/settings.htm

Mac OS X setup

Pull down the Apple menu and select System Preferences...
In System Preferences click Network.
In the drop-down Show: select the interface which connects to the cable modem (e.g. Built-in Ethernet).
Click tab TCP/IP, then:

In the drop-down Configure: select Using DHCP.
If your cable ISP specifies a Client ID, enter it in the box DHCP Client ID, otherwise clear the box to blank. NTL and Blueyonder do not require a Client ID.
Ensure the box Domain Name Servers is blank.
In the box Search Domains you may enter a default search domain for your ISP, e.g. ntlworld.com or blueyonder.co.uk or you may leave this box blank.

If the tab PPPoE is present, click it, then:

Ensure that Connect using PPPoE is unchecked.

If the tab AppleTalk is present, click it, then:

If you have a LAN with other Macintosh clients, check Make AppleTalk Active;
Otherwise, ensure Make AppleTalk Active is unchecked.

Click tab Proxies, then:

Ensure all Proxy or Firewall check-boxes are unchecked.
Check Use Passive FTP Mode (PASV).
In Bypass proxy settings for these Hosts & Domains enter 192.168.*
When/if you have a need to set a web proxy (not usually needed by default), you would do it by checking Web Proxy (HTTP), and entering the name of the proxy and its port number, usually 8080.

Click Apply Now.
Click Show All to exit Network.
Click Internet.
Click tab Email, then:

In the field Email Address: enter your preferred e-mail identity.
In the field Incoming Mail Server: enter your ISP's e-mail server name, and choose POP if it is a POP3 server or IMAP if it is an IMAP server.

For NTLworld, enter pop.ntlworld.com and choose POP.

In the field User Account ID, enter the user identifier that your ISP has given you for the purpose of logging in to the mail server above.
In the field Outgoing Mail Server: enter your ISP's SMTP server name.

For NTLworld, enter smtp.ntlworld.com

Click tab Web, then:

you may set all fields to your personal preferred values.

Click tab News, then:

In the field News Server: enter your ISP's NNTP server name.

For NTLworld, enter news.cable.ntlworld.com

Click Show All to exit Internet.
Pull down the System Prefs menu and select Quit System Prefs.