Cable Modems

Common Reasons for Cable Modem Signal Loss

The following are the most common causes of cable modem signal loss and steps you can take to troubleshoot and resolve the problem:

1. Physical Connection Problems

Loose cables are one of the most common causes of signal loss to a cable modem. Please verify that the coaxial cable coming from the wall outlet to the cable modem is firmly connected.


On most cable modems there is a light that indicates this cord has a good connection and is receiving Insight Broadband service. For example, a Scientific Atlanta Webstar cable modem will display a solid cable light, while or a solid online light will display on a Motorola Surfboard modem as shown below:


It may also be necessary to confirm that the Ethernet and USB cords are connected to the back of the modem and the computer. Try disconnecting the Ethernet and USB cords from the back of the modem and computer, and then reconnect them.



If you are using a router, unplug all cables from the router and then plug them back in.

After verifying all connections, it may be necessary to power cycle all devices in the network.

To power cycle devices, follow these steps:

A. Remove the power cords from the cable modem and router
B. Reconnect the power cord to the modem first and wait for the lights to come back on
C. Connect the power cord to the router and restart your computer

2. Proximity of Modem and Wireless Routers

Other common reasons for signal loss are associated with wireless connections. Wireless routers that are very close to cable modems can cause irregular signals resulting in dropped connections. It is recommended to have the wireless router as far from the cable modem as possible with a preferred minimum distance of approximately two feet.

3. Home Networking

A home network consists of a cable modem, a router and one or more computers. Sometimes after completing the above steps, everything looks like it should be working correctly. However, if an Internet connection cannot be established, it is necessary to gather a few details about the connection. Evaluate the configuration and make changes accordingly.

The following scenarios apply to wired and wireless connections.

Scenario 1:

There are three computers on the network. One computer is wired to the router (LAN) and the other two are connected wirelessly (WLAN). The wired computer and one of the wireless computers can connect to the Internet, but third cannot. In this situation, the wireless card for the computer that cannot connect may no longer be configured properly or is malfunctioning. To quickly establish if this computer can connect to the Internet, use an Ethernet cord to plug the computer directly into the router. If the computer connects to the Internet, follow the suggested troubleshooting steps as defined by the manufacturer of the wireless card.

Scenario 2:

Multiple computers are connected to the router and none of them can connect to the Internet. To troubleshoot, try connecting a computer directly to the modem by bypassing the router. In order to bypass a router and establish a connection with Insights network, follow the steps below in exactly the order listed:

A. Disconnect the power cord from the cable modem
B. Connect an Ethernet cord from the modem to the computer
C. Plug the power back into the cable modem
D. Restart the computer

The cable modem doesn't have the ability to identify a new connection unless it has been restarted. Once the direct connection is established, attempt to connect to the Internet. If the Internet connects after bypassing the router it may be necessary to consult the routers documented help topics. Further assistance with the router can be found on the manufacturers website or by contacting their technical support.

4. Firewalls and Internet Security Blocking Internet Access

Occasionally, software installed on computers can be responsible for blocking access to the Internet. Firewalls, Internet security software and anti-virus products are the most common causes of software-related situations that block Internet access.

Windows XP firewall, Norton Internet Security, McAfee, Trend Micro, and AVG are well known Internet security products that many consumers use. If you use one of these products and are unable to access the Internet, it may be necessary to disable the product and try to access the Internet.

NOTE: Disabling these products is done for troubleshooting purposes only. If you are able to connect with the product disabled, please be sure to contact the manufacturer for assistance in correcting the problem or use another product. It is very important to always have firewall and antivirus software operating on your computer.

Locate your PC Security provider below and follow the steps to temporarily disable your PC Security for troubleshooting purposes:

Windows XP

A. Log on as a user that is a member of the Administrators group
B. Open the Network Connections folder, right click the desired connection, and then click Properties
C. Click the Advanced tab, and remove the check next to Protect my computer and network by limiting or preventing access to this computer from the Internet
D. Click Yes to the dialog window that asks you to confirm your decision to disable the firewall

Norton Internet Security

A. Log on using an account with Adult or Supervisor rights
B. Open Norton Internet Security
C. On the left side of the window, click Internet Status, and then click Current Status
D. In the Current Status window, click Disable

Norton Personal Firewall

A. Open Norton Personal Firewall
B. On the left side of the window, click Internet Status, and then click Current Status
C. In the Current Status window, click Disable

You can also disable Norton Personal Firewall by right-clicking on the Norton Personal Firewall icon in the notification area of the taskbar and selecting disable.

McAfee Internet Security

A. Right-click the McAfee icon
B. Point to Personal Firewall, and then click Options
C. Click the Security tab
D. Set the Security Level by moving the slider to the desired level
E. Set Access to Low
F. Click OK to save changes

McAfee Firewall

A. Click Stop McAfee Firewall to disable the software
B. From the Welcome to McAfee Firewall screen, go to the Network Control Settings and select Allow All Traffic

Other firewall products, although not mentioned, will most likely be disabled or set to allow traffic in a similar way. More information and support should be found at the website of the manufacturer of the products.

5. Spyware, Viruses, or Peer-to-Peer Clients Limiting or Blocking Internet Access

Spyware and viruses are generally thought of as software that is installed on ones computer without their knowledge. Spyware collects personal information about users, and then relays that information to a computer collecting data.

Viruses alter the way a computer operates, without the permission or knowledge of the user, by hiding in other program files. Peer-to-peer and file sharing applications rely primarily on the computing power and bandwidth of the participants in the network. These applications give participants access to shared files on all connected computers. The primary affect can be extremely slow Internet speeds.

The following suggestions may help identify spyware, viruses and peer-to-peer clients on your computer.

Many programs can be found on the Internet that identify spyware on a computer system. Simply conducting a search for "spyware removal software" will yield multiple links to free applications that can identify and remove spyware. You may also read the PC/Internet Security section of our Help section. If your computer is suspected of being infected with spyware, it is extremely important to take the necessary steps to clean the computer.

Viruses can be identified and removed in much the same way as spyware. Using already installed antivirus software to complete real time scans will proactively keep your computer healthy. Like spyware, it is very important to diagnose a computer suspected of being infected with viruses as soon as possible.



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