This document describes how to use diagnostic information that you can find on your Motorola cable modem to determine if there may be problems with your cable Internet connection. Your cable Internet connection includes the coax cable that connects to the back of your cable modem and related cabling, connectors and splitters within your home. It also includes the connection from your home to the telephone pole and through your neighborhood to your service provider’s central site. Problems in any part of your cable Internet connection can result in degraded service or no service at all.
Your Motorola cable modem or cable modem gateway provides a number of readings that can be helpful in evaluating the quality of your cable Internet connection. If you experience problems with your cable modem Internet connection, these readings may help indicate where the problem lies.
Note that here we are not addressing your wireless connections, if any. We’re addressing the link between your cable modem and the Internet, which is best tested with a good Ethernet or wireless connection between your cable modem or gateway and the computer or other device you’re using for the readings discussed below.
This will bring you to the cable modem’s Basic Status and Settings page. Click the Advanced button in the upper right. This will bring you to the Status → Software page. Hover over the Status menu item, and then select the Connections submenu.
Look under the tab labeled Downstream Bonded Channels. You will see from 8 to 16 channels listed, 8 if you have an 8x4 cable modem and 16 if you have a 16x4 cable modem.
There may be from 1 to 16 channels shown with Lock Status ‘Locked’. For the ‘Locked’ channels, note the Power level(s) shown in the Pwr column. These should all be between -15 and +15dBmV; and they should also all be within three dB of each other. In the sample above, the power levels range from -4.1 to -2.5 dB, so they are within a range of 1.6dB.
Now note the Signal to Noise ratio(s) shown in the SNR (dB) column. The Signal to Noise ratios should also all be within three dB of each other. Recommended Signal to Noise ratios are:
|Power level (dBmV)||SNR|
|-15 to -6
-6 to +15
|33 dB or higher
30 dB or higher
Finally, note the Uncorrected column. Your cable modem uses sophisticated techniques to compensate for data packets that may have errors introduced by impairments on your connection. Some types of impairments do not affect power or signal to noise ratios, but do cause large numbers of uncorrected packets.
A small number of uncorrected packets won’t matter much. However, a large number, particularly if it is a significant fraction (roughly 20% or more) of the corrected packets value, can indicate a serious problem. What counts as a large number depends on the amount of traffic through your cable modem, but it will typically be in the thousands or tens of thousands.
Look under the tab labeled Upstream Bonded Channels. You should see four channels listed.
There may be from 1 to 4 channels shown with Lock Status ‘Locked’. For the ‘Locked’ channels, note the Power level(s) shown in the Pwr column. These should all be within three dB of each other. In the sample above, the power levels are within a range of 2.0dB.
Upstream power level limits depend on the number of upstream channels locked.
|Upstream Channels Locked||Power Limits (dBmV)|
2 to 4
35 to 57
35 to 54
For some networks, the power limits for 3 to 4 channels are 35 to 51 dBmV. Ideal levels are approximately 40 to 50 dBmV for single channels, 37 to 48 dBmV each for 2 to 4 channels.
In summary, you have a possible connection problem if any of these conditions is true:
If you have a possible connection problem, you should do the following. First, check the coax cable connection at the back of your cable modem. The connector should be tightened snugly. If you can, you should also check the cable connections to any coaxial wall outlet and/or coax splitter in your home.
If your problems persist after these checks, you should ask your service provider to check your connection. They may be able to resolve your issue by running checks from their central site without visiting your location.
If your connection problem continues after doing these checks, it is likely that your troubles with Internet connectivity are not due to your cable Internet connection. In that case please check your manual or the Motorola Mentor section of this website to see if there is a problem with your cable modem.