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Cable Modem Rear Panel 

Troubleshooting Tips

 

 

 

LAN  

Connect your Ethernet cable between this port and a 
computer or router. 
 

RESET 

Press this button for 5 seconds in the unlikely event 
that you need to restore factory default settings

.

 

 

RF 

Connect your coaxial cable line to this port

 
POWER 

Connect the supplied power cube to this port. 

 
ON/OFF 

Push the button in to turn the power ON. Push the 
button again to turn the power OFF

.

 

              

               

 

Please note the following: 

¾

  Do not block the modem vents in any way.  

¾

  Do not place the modem near a heating or air conditioning duct, in direct 

sunlight, anywhere susceptible to drastic temperature changes, or where it’s 
very hot or very cold. 

 
Front Panel LEDs 

Your cable modem has several lights on its front panel to help you monitor the cable 
modem’s status. 
 

LIGHT COLOR 

DESCRIPTION 

Power 

Green 

ON:   Power is supplied to the cable modem 
OFF: Power is not supplied to the cable modem 

DS 

Downstream 

sync

 

Green 

or

 

Blue 

Green Blinking:  Scanning for DS channel 
Green ON:          Synchronized on 1 channel only 
Blue Blinking:      Negotiating bonded channel(s)

Blue ON:             Bonded with 1 or more channels 
OFF: 

Downstream channel is inactive 

 

US 

Upstream sync

 

Green 

or

 

Blue 

Green Blinking:  Ranging is in progress 
Green ON:          Ranging is complete; operate on  

1 channel 

Blue Blinking:      Negotiating bonded channel(s)

Blue ON:             Bonded with 1 or more channels 
OFF: 

Upstream channel is inactive 

 

Online 

Green 

Blinking: Cable interface is acquiring IP, Time, and     

configuration 

ON:         Cable modem is online 
OFF: 

Cable modem is offline 

 

LAN 

Ethernet LAN 

port

 

Green 

Blinking: Data is flowing and the Ethernet link is 

connected 

Green: Connected 
OFF:       No Ethernet link detected 

 

 If Blue light blinks continuously, this indicates partial service (at least one designated       

channel has not completed bonding). You should still get high Internet speeds, but your 
cable modem service provider may want to know so they can adjust their network. 

 
 
 

 

Problem: 

  

I cannot access the Internet. What should I do first?

 

Solution: 

  Make sure that your Cable Modem’s MAC address is registered with your 

cable provider. When your provider’s representative or setup software asks 
for your MAC address, you can find the 

CM MAC

 address on your modem’s 

side label. If you are having a problem, you may need to check with your 
cable service provider to make sure the service provider set up its system 
properly for your cable modem. 

¾

    Make sure your Cable Modem’s Power button is ON and that the cable 

modem’s power cube is plugged into a live power outlet. 

¾

 

  Check your Cable Modem’s Ethernet and coaxial cable connections. Make 

sure the coaxial cable is tightly connected. Make sure that the Ethernet 
cable that connects a computer or router to your Cable Modem is plugged 
in all the way on both ends. 

¾

 

Power off your modem for at least 10 seconds, then power it back on. 

¾

 

Restart your computer or other devices connected to the Cable Modem. 
This ensures that they receive a correct IP address. 

 

Problem:  I cannot access the Internet. My Power light is on, my Downstream 

and Upstream lights are on or blinking, and my Online light is on.  

Solution: 

If you are using your computer’s Ethernet port, check that there is a good 
connection between your computer and the modem/router’s Ethernet port. 
Check that the light for that port is on or flashing.  

Problem:  I cannot access the Internet. My Power light is on, and my 

Downstream and Upstream lights are on or blinking. My Online light 
won’t stay on.  

Solution:     Try the following: 

¾

 Check to see that your cable TV is working. If it isn’t, contact your cable 

service provider. There may be a bad connection to the cable to your 
home or location. 

¾

 Check with your cable service provider to make sure that your cable data 

service is available and running. 

¾

 In some cases, the cable signal may be weak or noisy. If possible, see if 

the cable modem/router works better when it’s connected as near as 
possible to where the coaxial cable comes into your home. 

¾

 If you have a splitter between the cable modem/router and the wall, 

remove the splitter and connect the cable modem/router directly to the 
wall.  A splitter is a small device that has a single coax cable on one side 
and 2 coax cables on the other side. If this fixes the problem, you may 
need to get a better splitter. 

¾

 If the problem persists, you may need to ask your cable service provider to 

check the signal quality on your cable connection. 

 

Problem:  What do I do if my cable service provider wants me to access the 

Configuration Manager? 

Solution:  

Make sure you have a connection between your computer or other device 

and the cable modem. 

1

 

On your computer, open a browser and type in the address 

192.168.100.1

  Enter 

   

User Name:   

admin

            

      

Password:      

admin 

 

2

 

Now you will see status information about your cable modem and its  

connection that you can read back to your service provider. 

 

Problem:  What if I'm told that my Model 5370 cable modem isn't approved for my 

cable modem service? 

Solution: 

This modem has been certified by CableLabs and by Comcast, Time Warner 
Cable, and other cable modem service providers. You can often find a list of 
certified modems on the Web site of your cable service provider. Beware of 

installers who try to get you to use their cable modem instead of a Zoom 
cable modem. Some of these installers provide bad information because they 
are misinformed or because they earn a fee for providing their cable modem. 
If the installer tells you that a cable modem provided by him or the service 
provider is "free", that's almost never true. When in doubt, check the cable 
service provider’s Web site! 

 

In the unlikely event that you are told that your Zoom modem is not approved by 
your cable modem service, please email us at 

[email protected] 

or call us at 

(617)753-0963

 

 

Approval information for CableLabs, Comcast, and other service providers is 
available at 

www.zoomtel.com/cableOK

 

 

If You Need Help 

We encourage you to register your product and to notice the many support options 
available from Zoom. Please go to 

www.zoomtel.com/techsupport

  From here you can 

register your modem

 and/or 

contact our technical support experts

 and/or use our 

intelligent database 

SmartFacts

tm

 

and/or get 

warranty

 information.

 

US:

 (617) 753-0963 

Return of Defective Units 

Please contact your local distributor or retailer for factory-authorized repair or replacement of 
your in-warranty defective product. If you are unable to reach your distributor or retailer, you 
can contact Zoom Technical Support in the United States by calling: 

(617) 753-0963 

Please note that you are responsible for any charges (including brokerage or customs and 
duties) associated with shipping the defective unit to Zoom for repair. During the first year 
Zoom will pay return ground shipping to the customer in the continental U.S. After the first 
year you may be required to pay a shipping and handling fee. Any applicable customs, duties 
and brokerage charges to import the product are your responsibility

.  

Limited Warranty 

Zoom Telephonics, Inc. warrants this product against defects in material and workmanship for 
a warranty period of 2 years. To read the full warranty, please see 

www.zoomtel.com/cablewarranty

 

Safety Issues & Warnings 

WARNING:

  Risk of electric shock.  Do 

NOT

 expose to water or moisture. 

¾

 

The cable modem is a high-performance communications device designed for home and 
office environments.  

¾

 Do 

NOT

 use the cable modem outdoors.  Keep the cable modem in an environment that 

is between 0°C and 40°C (between 32°F and 104°F). 

¾

 

To avoid overheating the cable modem, do 

NOT

 place any object on top of the cable 

modem. 

¾

 Do 

NOT

 place the cable modem in a confined space. 

¾

 Do 

NOT

 restrict the flow of air around the cable modem. 

¾

 

The manufacturer assumes no liabilities for damage caused by any improper use of the 
cable modem. 

¾

 

Make sure the voltages and frequency of the power outlet matches the electrical rating 
labels on the power cube.   

 

FCC Statement  

This device complies with Class B Part 15 of the FCC Rules. Operation is subject to the following 
two conditions: (1) this device may not cause harmful interference, and (2) this device must accept 
any interference received, including interference that may cause undesired operation. Only Coaxial 
cables are to be used with this device in order to ensure compliance with FCC emissions limits. 
Accessories connected to this device by the user must comply with FCC Class B limits. The 
manufacturer is not responsible for any interference which results from use of improper cables, or 
which results from unauthorized changes or modifications to the device. 

 

Disclaimer 

Zoom Telephonics, Inc. (hereinafter “Zoom”) assumes no liabilities with respect to the contents of 
this document. Zoom also reserves the right to revise this document or update occasionally the 
content hereof without any obligation to notify any person of such revisions or amendments. 
Specifications subject to change without notice. 

 
 
 
 
 
 

 
 
 
 
 
 

2155-A   

 

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