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TM822G/NA: Troubleshoot Internet Connection

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How do I troubleshoot Internet connection issues with my TM822?

If Internet connection issues with the TM7822 arise, troubleshooting may resolve the issue, or may provide insight as to what is causing the issue.  This document provides helpful information for troubleshooting Internet connection issues with the TM822.

The following troubleshooting steps are to be followed in sequence:

  1. Check the physical connection
  2. Verify the LEDs
  3. Power Reset
  4. Verify the cable signal

NOTE: If the solutions provided in this document do not resolve the issue, please contact the cable operator for assistance.

Check the physical connection

  1. Verify that the TM822 power cord is connected from the power port of the TM822 to the power outlet.
  2. Verify that the coaxial cable is connected from the cable port of the TM822 to the cable outlet.
  3. Verify that the Ethernet cable is connected from the Ethernet port on the TM822 to the Ethernet port on the computer.

     User-added image

Verify the LEDs

With the proper setup, the Online LED should be on, and the Link LED should either be green or yellow.  If this is not the behavior that the TM822 is displaying, please refer to this table for more information regarding LED behavior.



Power Reset

  1. Shutdown the computer.
  2. Unplug the cable modem from the AC wall outlet and wait one minute.
  3. Plug the cable modem into the wall outlet.
  4. Wait until the Power, Receive, Send, and Online LEDs are solid.
  5. Restart the computer.

Verify the cable signal
  1. Launch a web browser, such as Internet Explorer, Firefox, or Safari.  Enter into the address box.  The Status page will appear.
  2. In the Downstream section, verify Power levels are within the acceptable range of - 15 dBmV to + 15 dBmV for each downstream channel. 

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  3. In the Downstream section, identify the Modulation and Power to verify SNR levels are within the acceptable range for each downstream channel. 

    Acceptable SNR Levels (dB)
    If QAM64SNR should be 23.5 dB or greater. 
    If QAM256 and DPL( -6 dBmV to +15 dBmV) SNR should be 30 dB or greater. 
    If QAM256 and DPL(-15 dBmV to -6 dBmV) SNR should be 33 dB or greater.   

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  4. In the Upstream section, identify the number of Upstream ChannelsChannel Type, and Symbolic Rate to verify thePower levels are within the acceptable range for each upstream channel. 

    Acceptable Upstream Power Levels (dBmV):

    Right click on the image to save it to your computer.

    Upstream Transmit Power Level
    ChannelUS Channel TypeSymbol RateAcceptable US Power Level
    TDMA1280 Ksym/sec+61 dBmV to 45 dBmV
    ATDMA2560 Ksym/sec+58 dBmV to 45 dBmV
    5120 Ksym/sec+57 dBmV to 45 dBmV
    TwoTDMA1280 Ksym/sec+58 dBmV to 45 dBmV
    ATDMA2560 Ksym/sec+55 dBmV to 45 dBmV
    5120 Ksym/sec+54 dBmV to 45 dBmV
    Three or moreTDMA1280 Ksym/sec+55 dBmV to 45 dBmV
    ATDMA2560 Ksym/sec+52 dBmV to 45 dBmV
    5120 Ksym/sec+51 dBmV to 45 dBmV
  5. Refresh the page at least twice to identify variations in SNR, Downstream Power, and Upstream Power.   

    NOTE: If the either of the signal levels are outside of the acceptable range, power cycle or factory reset the modem.  Factory resetting the modem will eliminate any customized settings.

  6. Contact the cable provider to adjust the signal level to the acceptable level range.

Acceptable Signal Levels
Recommended Max Downstream
Power Level (DPL)
Recommended Min Downstream
Power Level (DPL)
+15 dBmV-15 dBmV
Downstream Signal to Noise Ratio (SNR)
ModulationDownstream Power LevelAcceptable DS SNR
64 QAMn/a23.5 dB or greater
256 QAM
-6 dBmV to +15 BmV30 dB or greater
-6 dBmV to -15 dBmV33 dB or greater
Upstream Transmit Power Level
ChannelUS Channel TypeSymbol RateRecommended Max US Power LevelRecommended Min US Power Level
SingleTDMA1280 Ksym/sec+61 dBmV 45 dBmV
ATDMA2560 Ksym/sec+58 dBmV 45 dBmV
5120 Ksym/sec+57 dBmV 45 dBmV
TwoTDMA1280 Ksym/sec+58 dBmV 45 dBmV
ATDMA2560 Ksym/sec+55 dBmV 45 dBmV
5120 Ksym/sec+54 dBmV 45 dBmV
Three or moreTDMA1280 Ksym/sec+55 dBmV 45 dBmV
ATDMA2560 Ksym/sec+52 dBmV 45 dBmV
5120 Ksym/sec+51 dBmV 45 dBmV



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